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1

Laser-supported detonation waves and pulsed laser propulsion  

NASA Astrophysics Data System (ADS)

A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10 exp 4 K, 10 exp 2 atmospheres, 10 exp 7 w/sq cm) typically result in the creation of laser supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition if the LSD wave, laser plasma interactions in the LSD wave itself, and high temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low cost earth-to-orbit laser launch system. The program's approach to developing a high performance thruster, the double pulse planar thruster is summarized, and an overview is presented of some results obtained to date, along with a discussion of the many research questions still outstanding in this area.

Kare, Jordin T.

1989-08-01

2

Laser-supported detonation waves and pulsed laser propulsion  

NASA Astrophysics Data System (ADS)

A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (104 K, 102 atmospheres, 107 w/cm2) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition of the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the Program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research question still outstanding in this area.

Kare, Jordin

1990-07-01

3

Laser-supported detonation waves and pulsed laser propulsion  

SciTech Connect

A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10{sup 4} K, 10{sup 2} atmospheres, 10{sup 7} w/cm{sup 2}) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition of the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the Program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research question still outstanding in this area.

Kare, J. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1990-07-30

4

Laser-supported detonation waves and pulsed laser propulsion  

SciTech Connect

A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10{sup 4} K, 10{sup 2} atmospheres, 10{sup 7} w/cm{sup 2}) typically result in the creation of laser-supported detonation (LSD) waves. The thrust cycle thus involves a complex set of transient shock phenomena, including laser-surface interactions in the ignition if the LSD wave, laser-plasma interactions in the LSD wave itself, and high-temperature nonequilibrium chemistry behind the LSD wave. The SDIO Laser Propulsion Program is investigating these phenomena as part of an overall effort to develop the technology for a low-cost Earth-to-orbit laser launch system. We will summarize the program's approach to developing a high performance thruster, the double-pulse planar thruster, and present an overview of some results obtained to date, along with a discussion of the many research questions still outstanding in this area. 16 refs., 7 figs.

Kare, J.T.

1989-01-01

5

Numerical Analysis on Non-Equilibrium Mechanism of Laser-Supported Detonation Wave Using Multiply-Charged Ionization  

SciTech Connect

Laser-Supported Detonation (LSD), one type of Laser-Supported Plasma (LSP), is considered as the most important phenomena because it can generate high pressure and high temperature for laser absorption. In this study, I have numerically simulated the 1-D LSD waves propagating through a helium gas, in which Multiply-charged ionization model is considered for describing an accurate ionization process.

Shiraishi, Hiroyuki [Department of Mechanical Engineering, Daido Institute of Technology (Japan)

2006-05-02

6

Fundamental Properties of Non-equilibrium Laser-Supported Detonation Wave  

SciTech Connect

For developing laser propulsion, it is very important to analyze the mechanism of Laser-Supported Detonation (LSD), because it can generate high pressure and high temperature to be used by laser propulsion can be categorized as one type of hypersonic reacting flows, where exothermicity is supplied not by chemical reaction but by radiation absorption. I have numerically simulated the 1-D and Quasi-1-D LSD waves propagating through an inert gas, which absorbs CO2 gasdynamic laser, using a 2-temperature model. Calculated results show the fundamental properties of the non-equilibrium LSD Waves.

Shiraishi, Hiroyuki [Department of Mechanical Engineering, Daido Institute of Technology, 10-3 Taki-haru-cho, Minami-ku, Nagoya (Japan)

2004-03-30

7

Internal structure of laser supported detonation waves by two-wavelength Mach-Zehnder interferometer  

SciTech Connect

Characteristics of the internal structure of the laser supported detonation (LSD) waves, such as the electron density n{sub e} and the electron temperature T{sub e} profiles behind the shock wave were measured using a two-wavelength Mach-Zehnder interferometer along with emission spectroscopy. A TEA CO{sub 2} laser with energy of 10 J/pulse produced explosive laser heating in atmospheric air. Results show that the peak values of n{sub e} and T{sub e} were, respectively, about 2 x 10{sup 24} m{sup -3} and 30 000 K, during the LSD regime. The temporal variation of the laser absorption coefficient profile estimated from the measured properties reveals that the laser energy was absorbed perfectly in a thin layer behind the shock wave during the LSD regime, as predicted by Raizer's LSD model. However, the absorption layer was much thinner than a plasma layer, the situation of which was not considered in Raizer's model. The measured n{sub e} at the shock front was not zero while the LSD was supported, which implies that the precursor electrons exist ahead of the shock wave.

Shimamura, Kohei; Kawamura, Koichi; Fukuda, Akio; Wang Bin; Yamaguchi, Toshikazu; Komurasaki, Kimiya [Department of Advanced Energy, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8561 (Japan); Hatai, Keigo; Fukui, Akihiro; Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

2011-04-15

8

Numerical Analysis on Thermal Non-Equilibrium Process of Laser-Supported Detonation Wave in Axisymmetric Nozzle  

SciTech Connect

Numerical Analyses on Laser-Supported Plasma (LSP) have been performed for researching the mechanism of laser absorption occurring in the laser propulsion system. Above all, Laser-Supported Detonation (LSD), categorized as one type of LSP, is considered as one of the most important phenomena because it can generate high pressure and high temperature for performing highly effective propulsion. For simulating generation and propagation of LSD wave, I have performed thermal non-equilibrium analyses by Navier-stokes equations, using a CO{sub 2} gasdynamic laser into an inert gas, where the most important laser absorption mechanism for LSD propagation is Inverse Bremsstrahlung. As a numerical method, TVD scheme taken into account of real gas effects and thermal non-equilibrium effects by using a 2-temperature model, is applied. In this study, I analyze a LSD wave propagating through a conical nozzle, where an inner space of an actual laser propulsion system is simplified.

Shiraishi, Hiroyuki [Daido Institute of Technology, Dept. of Mechanical Engineering 10-3 Takiharu-cho, Minami-ku, Nagoya 457-8530 (Japan)

2008-04-28

9

Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation  

SciTech Connect

In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter.

Gan, Li, E-mail: ligan0001@gmail.com; Mousen, Cheng; Xiaokang, Li [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha (China)] [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha (China)

2014-03-15

10

Predicting propagation limits of laser-supported detonation by Hugoniot analysis  

NASA Astrophysics Data System (ADS)

Termination conditions of a laser-supported detonation (LSD) wave were investigated using control volume analysis with a Shimada–Hugoniot curve and a Rayleigh line. Because the geometric configurations strongly affect the termination condition, a rectangular tube was used to create the quasi-one-dimensional configuration. The LSD wave propagation velocity and the pressure behind LSD were measured. Results reveal that the detonation states during detonation and at the propagation limit are overdriven detonation and Chapman–Jouguet detonation, respectively. The termination condition is the minimum velocity criterion for the possible detonation solution. Results were verified using pressure measurements of the stagnation pressure behind the LSD wave.

Shimamura, Kohei; Ofosu, Joseph A.; Komurasaki, Kimiya; Koizumi, Hiroyuki

2015-01-01

11

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Dynamics and modelling of shock waves formed during propagation of a laser-supported detonation wave in argon  

NASA Astrophysics Data System (ADS)

Experimental and theoretical investigations are reported of axial and radial shock waves formed in argon during propagation of an optical detonation wave maintained by a CO2 laser pulse. The experimental results are not be described by the standard self-similar law of motion of a cylindrical shock wave, but instead they agree well with the results of self-consistent two-dimensional numerical calculations. This is attributed to displacement of a hot gas along the beam axis out of the zone of absorption of laser radiation. The distance R travelled by the front of the resultant radial shock wave during a time interval t is described by the law R propto t?, where 0.55

Anisimov, V. N.; Vorob'ev, V. A.; Grishina, V. G.; Derkach, O. N.; Kanevskii, M. F.; Sebrant, A. Yu; Stepanova, M. A.; Chernov, S. Yu

1995-08-01

12

Detonation waves in trinitrotoluene  

Microsoft Academic Search

Fabry-Perot, ORVIS, and VISAR laser interferometry are used to obtain nanosecond time resolved particle velocity histories of the free surfaces of copper and tantalum discs accelerated by detonating trinitrotoluene (TNT) charges and of the interfaces between TNT detonation products and lithium fluoride crystals. TNT detonation reaction zone profiles are measured for self-sustaining detonation and piston supported overdriven (supracompressed) waves. The

John W. Kury; R. Don Breithaupt; Craig M. Tarver

1999-01-01

13

Review of Propulsion Applications of Detonation Waves  

Microsoft Academic Search

Applications of detonations to propulsion are reviewed. First, the advantages of the detonation cycle over the constant pressure combustion cycle, typical of conventional propulsion engines, are discussed. Then the early studies of standing normal detonations, intermittent (or pulsed) detonations, rotating detonations, and oblique shock-induced detonations are reviewed. This is followed by a brief discussion of detonation thrusters, laser- supported detonations

K. Kailasanath

2000-01-01

14

Detonation waves in triaminotrinitrobenzene  

Microsoft Academic Search

FabryâPerot laser interferometry is used to obtain nanosecond time resolved particle velocity histories of the free surfaces of copper, tantalum, or magnesium disks driven by detonating triaminotrinitrobenzene (TATB)-based charges and of the interfaces between detonating TATB and transparent salt crystals. Detonation reaction zone profiles are measured for self-sustaining detonation waves propagating through various thicknesses of LX-17 (92.5% TATB and 7.5%

Craig M. Tarver; John W. Kury; R. Don Breithaupt

1997-01-01

15

Detonation waves in trinitrotoluene  

Microsoft Academic Search

.   Fabry-Perot, ORVIS, and VISAR laser interferometry are used to obtain nanosecond time resolved particle velocity histories\\u000a of the free surfaces of copper and tantalum discs accelerated by detonating trinitrotoluene (TNT) charges and of the interfaces\\u000a between TNT detonation products and lithium fluoride crystals. TNT detonation reaction zone profiles are measured for self-sustaining\\u000a detonation and piston supported overdriven (supracompressed) waves.

John W. Kury; R. Don Breithaupt; Craig M. Tarver

1999-01-01

16

Detonation waves in triaminotrinitrobenzene  

Microsoft Academic Search

Fabry–Perot laser interferometry is used to obtain nanosecond time resolved particle velocity histories of the free surfaces of copper, tantalum, or magnesium disks driven by detonating triaminotrinitrobenzene (TATB)-based charges and of the interfaces between detonating TATB and transparent salt crystals. Detonation reaction zone profiles are measured for self-sustaining detonation waves propagating through various thicknesses of LX-17 (92.5% TATB and 7.5%

Craig M. Tarver; John W. Kury; R. Don Breithaupt

1997-01-01

17

Oblique detonation wave ramjet  

NASA Technical Reports Server (NTRS)

Two conceptual designs of the oblique detonation wave ramjet are presented. The performance is evaluated for stoichiometric hydrogen-air equivalence ratios of phi = 1/3, 2/3 and 1 for a range of flight Mach numbers from 6 to 10.

Morrison, R. B.

1980-01-01

18

Photoionization in the Precursor of Laser Supported Detonation by Ultraviolet Radiation  

SciTech Connect

The propagation mechanism of laser-supported detonation (LSD) is important for designing laser propulsion for a detonation type thruster. The purpose of this work to was to confirm that photo-ionization in precursor is the predominant LSD sustainment mechanism. First of all, we tried to investigate the dependency of LSD duration on ambient gas species, air and argon. We took a series of high-speed images using the laser shadow-graphy. Besides, to estimate the UV photons emitted from the plasma, we used plasma emission spectroscopy and determined the electron temperature and density. As a result, the LSD duration of argon plasma and air plasma are 0.7 {mu}s and 0.3 {mu}s, resp. Besides, argon plasma emitted 10{sup 10} to 10{sup 14} photons/seconds, which was higher than air plasma. These results reveal that LSD propagation depends on the photon-contributing photoionization. The threshold photon-emission rate of LSD termination gives the elucidation of the LSD termination condition.

Shimamura, Kohei; Michigami, Keisuke; Wang, Bin; Komurasaki, Kimiya [Department of Advanced Energy, University of Tokyo 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba, 277-8561 (Japan); Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan)

2011-11-10

19

Gaseous detonation initiation via wave implosion  

Microsoft Academic Search

Efficient detonation initiation is a topic of intense interest to designers of pulse detonation engines. This experimental work is the first to detonate propane-air mixtures with an imploding detonation wave and to detonate a gas mixture with a non-reflected, imploding shock. In order to do this, a unique device has been developed that is capable of generating an imploding toroidal

Scott Irving Jackson

2005-01-01

20

Mach reflection of spherical detonation waves  

SciTech Connect

When two detonation waves collide, the shape of the wave front at their intersection can be used to categorize the flow as regular or irregular reflection. In the case of regular reflection, the intersection of the waves forms a cusp. In the case of irregular reflection, the cusp is replaced by a leading shock locus that bridges the incident waves. Many workers have studied irregular or Mach reflection of detonation waves, but most of the their experimental work has focused on the interaction of plane detonation waves. Reflection of spherical detonation waves has received less attention. This study also differs from previous work in that the focus is to measure the relationship between the detonation velocity and the local wave curvatue for irregular reflection of spherical detonation waves. Two explosives with different detonation properties, PBX 9501 and PBX 9502, are compared.

Hull, L.M.

1993-07-01

21

Airbreathing Rotating Detonation Wave Engine Cycle Analysis  

E-print Network

Static pressure PDE Pulsed detonation engine q Dynamic pressure r Radial distance behind wave front R Gas to pulsed detonation engines (PDEs). With its annular combustion chamber, the RDWE has the potential

Texas at Arlington, University of

22

Detonation Wave Propagation in an Ejector-Augmented Pulse Detonation Rocket  

E-print Network

Detonation Wave Propagation in an Ejector-Augmented Pulse Detonation Rocket Tae-Hyeong Yi , Donald, TX 76019, USA The propagation of a detonation wave in an ejector-augmented pulse detonation rocket. An interaction between a primary flow from a pulse detonation rocket embedded in a mixing chamber and an incoming

Texas at Arlington, University of

23

Laser-supported detonation waves and pulsed laser propulsion  

Microsoft Academic Search

A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (104 K, 102 atmospheres, 107 w\\/cm2) typically result in

Jordin Kare

1990-01-01

24

Laser-supported detonation waves and pulsed laser propulsion  

Microsoft Academic Search

A laser thermal rocket uses the energy of a large remote laser, possibly ground-based, to heat an inert propellant and generate thrust. Use of a pulsed laser allows the design of extremely simple thrusters with very high performance compared to chemical rockets. The temperatures, pressures, and fluxes involved in such thrusters (10 exp 4 K, 10 exp 2 atmospheres, 10

Jordin T. Kare

1989-01-01

25

Gaseous detonation initiation via wave implosion  

NASA Astrophysics Data System (ADS)

Efficient detonation initiation is a topic of intense interest to designers of pulse detonation engines. This experimental work is the first to detonate propane-air mixtures with an imploding detonation wave and to detonate a gas mixture with a non-reflected, imploding shock. In order to do this, a unique device has been developed that is capable of generating an imploding toroidal detonation wave inside of a tube from a single ignition point without any obstruction to the tube flow path. As part of this study, an initiator that creates a large-aspect-ratio planar detonation wave in gas-phase explosive from a single ignition point has also been developed. The effectiveness of our initiation devices has been evaluated. The minimum energy required by the imploding shock for initiation was determined to scale linearly with the induction zone length, indicating the presence of a planar initiation mode. The imploding toroidal detonation initiator was found to be more effective at detonation initiation than the imploding shock initiator, using a comparable energy input to that of current initiator tubes.

Jackson, Scott Irving

26

Detonation wave compression in gas turbines  

NASA Technical Reports Server (NTRS)

A study was made of the concept of augmenting the performance of low pressure ratio gas turbines by detonation wave compression of part of the flow. The concept exploits the constant volume heat release of detonation waves to increase the efficiency of the Brayton cycle. In the models studied, a fraction of the compressor output was channeled into detonation ducts where it was processed by transient transverse detonation waves. Gas dynamic studies determined the maximum cycling frequency of detonation ducts, proved that upstream propagation of pressure pulses represented no problems and determined the variations of detonation duct output with time. Mixing and wave compression were used to recombine the combustor and detonation duct flows and a concept for a spiral collector to further smooth the pressure and temperature pulses was presented as an optional component. The best performance was obtained with a single firing of the ducts so that the flow could be re-established before the next detonation was initiated. At the optimum conditions of maximum frequency of the detonation ducts, the gas turbine efficiency was found to be 45 percent while that of a corresponding pressure ratio 5 conventional gas turbine was only 26%. Comparable improvements in specific fuel consumption data were found for gas turbines operating as jet engines, turbofans, and shaft output machines. Direct use of the detonation duct output for jet propulsion proved unsatisfactory. Careful analysis of the models of the fluid flow phenomena led to the conclusion that even more elaborate calculations would not diminish the uncertainties in the analysis of the system. Feasibility of the concept to work as an engine now requires validation in an engineering laboratory experiment.

Wortman, A.

1986-01-01

27

High order hybrid numerical simulations of two dimensional detonation waves  

NASA Technical Reports Server (NTRS)

In order to study multi-dimensional unstable detonation waves, a high order numerical scheme suitable for calculating the detailed transverse wave structures of multidimensional detonation waves was developed. The numerical algorithm uses a multi-domain approach so different numerical techniques can be applied for different components of detonation waves. The detonation waves are assumed to undergo an irreversible, unimolecular reaction A yields B. Several cases of unstable two dimensional detonation waves are simulated and detailed transverse wave interactions are documented. The numerical results show the importance of resolving the detonation front without excessive numerical viscosity in order to obtain the correct cellular patterns.

Cai, Wei

1993-01-01

28

On the Existence of Pathological Detonation Waves  

NASA Astrophysics Data System (ADS)

Pathological detonation waves with velocities greater than Chapman-Jouguet (C-J) have been proposed theoretically but never observed experimentally in gaseous, liquid or solid explosives. Two types of pathological chemical reaction zones have been identified within the Zeldovich - von Neumann - Doring (ZND) model: an exothermic chemical decomposition with a mole decrease from the von Neumann spike state to the C-J state; and an exothermic reaction followed by an endothermic reaction (eigenvalue detonation). The high temperatures reached in detonation reaction zones cause sufficient radial and atom formation to insure that enough moles are formed in gaseous 2H2 + O2 detonations. Aluminized explosives exhibit a slight mole decrease when the solid aluminum particles are oxidized, but this does not negate the large mole increase that occurs during explosive decomposition. Porous solid explosives whose products form with more cold compression energy than that of the solid are still a possibility for pathological detonation. Eigenvalue detonations have been postulated for H2 + Cl2 gas phase detonations and for plastic bonded solid explosives if endothermic binder decomposition follows exothermic explosive decomposition. Chemical kinetic and physical arguments are presented to eliminate these possible pathological detonations. In the case of H2 + Cl2, highly vibrationally excited HCl molecules dissociate Cl2 molecules during the exothermic portion of the reaction zone rather than later in the flow process. In the plastic bonded explosives, the binders are located on the surfaces of explosive particles and thus are exposed to hot spots created by the three-dimensional Mach stem shock front. Any remaining binder material rapidly reacts in collisions with the high, vibrationally excited reaction products formed during explosive decomposition. Therefore eigenvalue detonations are extremely unlikely to occur in gaseous, liquid or solid explosives.

Tarver, Craig M.

2004-07-01

29

On the Existence of Pathological Detonation Waves  

SciTech Connect

Pathological detonation waves with velocities greater than Chapman-Jouguet (C-J) have been proposed theoretically but never observed experimentally in gaseous, liquid or solid explosives. Two types of pathological chemical reaction zones have been identified within the Zeldovich-von Neumann-Doring (ZND) model: an exothermic chemical decomposition with a mole decrease during from the von Neumann spike state to the C-J state and an exothermic reaction followed by an endothermic reaction (eigenvalue detonation). The high temperatures reached in detonation reaction zones cause sufficient radial and atom formation to insure overall mole increases in gaseous H{sub 2} + O{sub 2} detonations. Aluminized explosives exhibit a slight mole decrease when the solid aluminum particles are oxidized, but this does not negate the large mole increase that occurs during explosive decomposition. Porous solid explosives whose products form with more cold compression energy than that of the solid are an unlikely possibility for pathological detonation. Eigenvalue detonations have been postulated for H{sub 2} + Cl{sub 2} gas phase detonations and for plastic bonded solid explosives if endothermic binder decomposition follows exothermic explosive decomposition. Chemical kinetic and physical arguments are presented to eliminate these possible pathological detonations. In the case of H{sub 2} + Cl{sub 2}, highly vibrationally excited HCl molecules dissociate Cl{sub 2} molecules during the exothermic portion of the reaction zone rather than later in the flow process. In the plastic bonded explosives, the binders are located on the surfaces of explosive particles and thus are exposed to ''hot spots'' created by the three-dimensional Mach stem shock front. Any remaining binder material rapidly reacts in collisions with the high, vibrationally excited reaction products formed during explosive decomposition. Therefore eigenvalue detonations are extremely unlikely to occur in gaseous, liquid or solid explosives.

Tarver, C M

2003-07-11

30

Mach reflection of detonation waves  

NASA Astrophysics Data System (ADS)

The diffraction of a nominally planar gaseous detonation at a wedge was investigated to determine the critical wedge angle for transition from regular to Mach reflection. Experiments were conducted in a square 83-mm cross-section detonation tube using stoichiometric mixtures of hydrogen-oxygen at 0.2 bars. Experimental results for the triple-point trajectory angle produced during Mach reflection were obtained using the smoke foil technique and are compared with analytic calculations made using three-shock theory and the oblique detonation polars. Measurements of the cell size behind the overdriven Mach stem are also reported. Both analytic and experimental results are compared with work from previous investigations to address apparent discrepancies in the existing literature.

Meltzer, J.; Shepherd, J. E.; Akbar, R.; Sabet, A.

31

Analytical study of laser supported combustion waves in hydrogen  

NASA Technical Reports Server (NTRS)

A one-dimensional energy equation, with constant pressure and area, was used to model the LSC wave. This equation balances convection, conduction, laser energy absorption, radiation energy loss and radiation energy transport. Solutions of this energy equation were obtained to give profiles of temperature and other properties, as well as the relation between laser intensity and mass flux through the wave. The flow through the LSC wave was then conducted through a variable pressure, variable area streamtube to accelerate it to high speed, with the propulsion application in mind. A numerical method for coupling the LSC wave model to the streamtube flow was developed, and a sample calculation was performed. The result shows that 42% of the laser power has been radiated away by the time the gas reaches the throat. It was concluded that in the radially confined flows of interest for propulsion applications, transverse velocities would be less important than in the unconfined flows where air experiments have been conducted.

Kemp, N. H.; Root, R. G.

1977-01-01

32

AIAA 95-2197 Experimental Investigation of Pulse Detonation Wave  

E-print Network

AIAA 95-2197 Experimental Investigation of Pulse Detonation Wave Phenomenon S. B. Stanley, W. Scott to develop an operational Pulse Detonation Engine. The study was conducted in a simple cylindrical test.0INTRODUCTION Pulse Detonation Engines show a great deal of promise for a variety of applications. The most

Texas at Arlington, University of

33

Steady Detonation Wave Solutions Under the Reaction Heat Effect  

NASA Astrophysics Data System (ADS)

The dynamics of the steady detonation wave is studied in the frame of the kinetic theory for a binary reacting mixture undergoing a chemical reaction of type A + A ? B + B. The influence of the reaction heat on the detonation wave structure is investigated for the first time. Some numerical results are provided for a generic symmetric chemical reaction of exothermic and endothermic type.

Carvalho, Filipe; Soares, Ana Jacinta

2010-04-01

34

DNS of Detonation Wave and Isotropic Turbulence Interaction  

E-print Network

DNS of Detonation Wave and Isotropic Turbulence Interaction Hari Narayanan Nagarajan , Luca Massa setup are described, followed in §III by a presentation of the validation tests and its results. The DNS

Texas at Arlington, University of

35

Propagation of Axially Symmetric Detonation Waves  

SciTech Connect

We have studied the non-ideal propagation of detonation waves in LX-10 and in the insensitive explosive TATB. Explosively-driven, 5.8-mm-diameter, 0.125-mm-thick aluminum flyer plates were used to initiate 38-mm-diameter, hemispherical samples of LX-10 pressed to a density of 1.86 g/cm{sup 3} and of TATB at a density of 1.80 g/cm{sup 3}. The TATB powder was a grade called ultrafine (UFTATB), having an arithmetic mean particle diameter of about 8-10 {micro}m and a specific surface area of about 4.5 m{sup 2}/g. Using PMMA as a transducer, output pressure was measured at 5 discrete points on the booster using a Fabry-Perot velocimeter. Breakout time was measured on a line across the booster with a streak camera. Each of the experimental geometries was calculated using the Ignition and Growth Reactive Flow Model, the JWL++ Model and the Programmed Burn Model. Boosters at both ambient and cold (-20 C and -54 C) temperatures have been experimentally and computationally studied. A comparison of experimental and modeling results is presented.

Druce, R L; Roeske, F; Souers, P C; Tarver, C M; Chow, C T S; Lee, R S; McGuire, E M; Overturf, G E; Vitello, P A

2002-06-26

36

Application of steady and unsteady detonation waves to propulsion  

NASA Astrophysics Data System (ADS)

The present work investigates the applications of steady and unsteady detonation waves to air-breathing propulsion systems. The efficiency of ideal detonation-based propulsion systems is first investigated based on thermodynamics. We reformulate the Hugoniot analysis of steady combustion waves for a fixed initial stagnation state to conclude that steady detonation waves are less desirable than deflagrations for propulsion. However, a thermostatic approach shows that unsteady detonations have the potential for generating more work than constant-pressure combustion. The subsequent work focuses on specific engine concepts. A flow path analysis of ideal steady detonation engines is conducted and shows that their performance is limited and poorer than that of the ideal ramjet or turbojet engines. The limitations associated with the use of a steady detonation in the combustor are drastic and such engines do not appear to be practical. This leads us to focus on unsteady detonation engines, i.e., pulse detonation engines. The unsteady generation of thrust in the simple configuration of a detonation tube is first analyzed using gas dynamics. We develop one of the first models to quickly and reliably estimate the impulse of a pulse detonation tube. The impulse is found to scale directly with the mass of explosive in the tube and the square root of the energy release per unit mass of the mixture. Impulse values for typical fuel-oxidizer mixtures are found to be on the order of 160 s for hydrocarbon-oxygen mixtures and 120 s for fuel-air mixtures at standard conditions. These results are then used as a basis to develop the first complete system-level performance analysis of a supersonic, single-tube, air-breathing pulse detonation engine. We show that hydrogen- and JP10-fueled pulse detonation engines generate thrust up to a Mach number of 4, and that the specific impulse decreases quasi-linearly with increasing flight Mach number. Finally, we find that the performance of our pulse detonation engine exceeds that of the ramjet below a Mach number of 1.35.

Wintenberger, Eric

37

The formation of fast deflagration waves from detonation failure  

NASA Astrophysics Data System (ADS)

When irregular cellular detonations are transmitted though a section of a shock tube lined with porous walls, it has been observed experimentally that sufficient attenuation of the transverse shock waves causes the detonation to fail, manifested by a decoupling between the shock and reaction zone structures. The resulting reaction structure consists of a weaken, near steady one-dimensio nal shock wave that trails a near steady fast deflagration wave which runs at approximately 40 percent of the original Chapman-Jouget detonation velocity. We propose that the failure of the detonation in these circumstances is due to a one-dimensional instability. We analyze the mechanism of one-dimensional Chapman-Jouget detonation failure and the resulting reaction structure in a model with a three-step chain-branchi ng reaction. Failure arises due to a sufficiently large-amplitude instability which causes the shock temperature to drop below the chain-branching cross-over temperature. The resulting structure is similar to that observed in the porous tube wall experiments, with a fast deflagration running at approximately 50 percent of the original Chapman-Jouget detonation velocity.

Gorchkov, Viktor; Short, Mark

2003-11-01

38

The role of compressible turbulence in detonation waves  

NASA Astrophysics Data System (ADS)

Detonation waves are supersonic combustion waves, observable in both terrestrial and astrophysical settings. The present study investigates experimentally and numerically the turbulent structure of gaseous detonation waves. Due to hydrodynamic instabilities, the front exhibits pulsations over a large range of scales. During the negative pulsations of the leading front, chemical induction delay times increase dramatically. Nevertheless, the gas shocked during these negative pulsations ignites before its adiabatic ignition delay times, following the turbulization of burned/unburned gas interfaces and increase of transport rates. The nature of the turbulent interactions responsible for the gas ignition are identified. Shock-shock interactions produce vorticity layers which enhance mixing via Kelvin-Helmholtz instabilities. Shock-density layer interactions favor Richtmyer-Meshkov instabilities. Large vortical flows entrain hot reacted gases into un-reacted gases and enhance their burning rates. A statistical description of the turbulent energy budget within the detonation wave structure is obtained from the two-dimensional numerical simulations.

Radulescu, Matei I.; Sharpe, Gary J.; Law, Chung K.

2004-11-01

39

On the influence of low initial pressure and detonation stochastic nature on Mach reflection of gaseous detonation waves  

NASA Astrophysics Data System (ADS)

The two-dimensional, time-dependent and reactive Navier-Stokes equations were solved to obtain an insight into Mach reflection of gaseous detonation in a stoichiometric hydrogen-oxygen mixture diluted by 25 % argon. This mixture generates a mode-7 detonation wave under an initial pressure of 8.00 kPa. Chemical kinetics was simulated by an eight-species, forty-eight-reaction mechanism. It was found that a Mach reflection mode always occurs for a planar detonation wave or planar air shock wave sweeping over wedges with apex angles ranging from to . However, for cellular detonation waves, regular reflection always occurs first, which then transforms into Mach reflection. This phenomenon is more evident for detonations ignited under low initial pressure. Low initial pressure may lead to a curved wave front, that determines the reflection mode. The stochastic nature of boundary shape and transition distance, during deflagration-to-detonation transition, leads to relative disorder of detonation cell location and cell shape. Consequently, when a detonation wave hits the wedge apex, there appears a stochastic variation of triple point origin and variation of the angle between the triple point trajectory and the wedge surface. As the wedge apex angle increases, the distance between the triple point trajectory origin and the wedge apex increases, and the angle between the triple point trajectory and the wedge surface decreases exponentially.

Wang, C. J.; Guo, C. M.

2014-09-01

40

Mechanism of Detonation Wave propagation in PBX with Energetic Binder  

NASA Astrophysics Data System (ADS)

The complex phenomena of Detonation Wave (DW) propagation in PBX of 82% of HMX, with successively HTPB, as inert binder, and GAP as Energetic Binder (EB), with an initial density 99.5% TMD was studied. A thin optical multifibre strip (250 ?m each fibre), connected to a fast electronic streak camera, allows the nanosecond temporal resolution not only of the behavior of coarse HMX particles, surrounded by binder, but also the fine geometrical structure of detonation and its subsequent shock waves. The results obtained with micro gap and corner turning tests, prove the influence of EB in the mechanisms of DW formation in PBX, especially in the interaction zone between binder and particles. Detonation in PBX with GAP binder shows the shock front interacting earlier in the EB space, between the coarse particles, and DW oscillations with a mean period of 23±5 ns, 1.5 times less than those observed in PBX with HTPB.

Plaksin, I.; Campos, J.; Mendes, R.; Ribeiro, J.; Gois, J.

2000-04-01

41

Characterization of Detonation Wave Propagation in LX17 Near the Critical Diameter  

Microsoft Academic Search

A new Detonation Profile Test (DPT) was developed to measure simultaneously the detonation wave breakout profile and the average detonation velocity at the breakout surface. The test evaluated small cylindrical samples with diameter up to 19.08 mm and length up to 33 mm. The experiment involved initiating a LX-17 cylindrical specimen and recording the wave breakout using a fast streaking

T. D. Tran; C. M. Tarver; J. Maienschein; P. Lewis; R Pastrone; R. S. Lee; F. Roeske

2002-01-01

42

Simulations of a Detonation Wave in Transverse Magnetic Fields  

NASA Astrophysics Data System (ADS)

Numerical simulations of magneto-hydrodynamic (MHD) effects on detonation wave structures are performed, with applications to flow control and MHD power extraction in Pulse Detonation Engines (PDE) and their design variations. In contrast to prior studies of MHD interactions in PDEs,ootnotetextCambier, et al., AIAA-2008-4688 the effects of the finite relaxation length scale for ionization on the stability of the detonation wave are examined. Depending on the coupling parameters, the magnetic field can quench the detonation and effectively act as a barrier to its propagation. Conversely, an applied transient magnetic field can exert a force on a pre-ionized gas and accelerate it. The dynamics are subject to non-linear effects; a propagating transverse magnetic field will initially exert a small force if the gas has a low conductivity and the magnetic Reynolds number (Rem) is low. Nevertheless, the gas accelerated by the "piston" action of the field can pre-heat the ambient gas and increase its conductivity. As the wave progresses, Rem increases and the magnetic field becomes increasingly effective. The dynamics of this process are examined in detail with a high-order shock-capturing method and full kinetics of combustion and ionization. The complex chemical kinetics calculations are ported onto a GPU using the CUDA language, and computational performance is compared with standard CPU-based computations.

Cole, Lord; Karagozian, Ann; Cambier, Jean-Luc

2010-11-01

43

Re-Initiation Mechanisms of a Detonation Wave in the PDE Initiator Using a Reflecting Board  

NASA Astrophysics Data System (ADS)

Quick initiation of a detonation wave in a combustion chamber is important to realize high-performance pulse detonation engine. A possible method is to generate a detonation wave in a pre-detonator and release the detonation wave into the chamber. In this paper, a reflecting board is installed in the combustion chamber near the pre-detonator exit where the tube diameter expands abruptly. It prevents the detonation wave from disappearing at the expanding region near the tube exit. The re-initiation mechanisms of a detonation wave near the reflecting board were observed by using the soot film method. Main results obtained in this study are in the followings: Re-initiation of a detonation wave due to the Mach reflection of a shock wave is observed on the surface of the reflecting board and the propagation promoting effect is observed. The effectiveness of the reflecting board is a strong function of the clearance between the pre-detonator exit and the reflecting board, and the promotion effect sharply decreases with increasing the clearance beyond the distance, in which the incident planar detonation wave maintains. By equipping with a reflective board with a suitable clearance, the critical cell size increases by 2 or 3 times.

Wakita, Masashi; Numakura, Ryusuke; Ito, Yusuke; Nagata, Harunori; Totani, Tsuyoshi; Kudo, Isao

44

Numerical Study of Unsteady Detonation Wave Propagation in a Supersonic Combustion Chamber  

E-print Network

, of which each mode has unique features and operation ranges: an ejector aug- mented pulsed detonation (ODWE) mode and a pure pulsed detonation rocket mode. One of main advantages of this concept and volume of the vehicle. A detailed analysis on the pulsed detonation wave engine mode is necessary since

Texas at Arlington, University of

45

Shock wave dynamics of novel aluminized detonations and empirical model for temperature evolution from post-detonation combustion fireballs  

NASA Astrophysics Data System (ADS)

Optical forensics of explosion events can play a vital role in investigating the chain of events leading up to the explosion by possibly identifying key spectral characteristics and even molecules in the post-detonation fireball that may serve as the fingerprint for a particular explosive type used. This research characterizes the blast wave and temperature evolution of an explosion fireball in order to improve the classification of aluminized conventional munitions based on a single explosive type such as RDX. High speed 4 kHz visible imagery is collected for 13 field detonations of aluminized novel munitions to study fireball and shock wave dynamics. The 238 mus temporal resolution visible imagery and the 12 ms temporal resolution FTS spectra are the data sets upon which shock wave dynamics and the time dependence of the fireball temperature are studied, respectively. The Sedov-Taylor point blast theory is fitted to data where a constant release (s = 1) of energy upon detonation suggests shock energies of 0.5--8.9 MJ corresponding to efficiencies of 2--15 percent of the RDX heats of detonation with blast dimensionalities indicative of the spherical geometry observed in visible imagery. A drag model fit to data shows initial shock wave speeds of Mach 4.7--8.2 and maximum fireball radii ranging from 4.3--5.8 m with most of the radii reached by 50 ms upon detonation. Initial shock speeds are four times lower than theoretical maximum detonation speed of RDX and likely contributes to the low efficiencies. An inverse correlation exists between blast wave energy and overall aluminum or liner content in the test articles. A two-color best fit Planckian is used to extract temperature profiles from collected Fourier-transform spectrometer spectra. The temperatures decay from initial values of 1290--1850 K to less than 1000 K within 1 s after detonation. A physics-based low-dimensionality empirical model is developed to represent the temperature evolution of post-detonation combustion fireballs. Using a radiative cooling term and a secondary combustion term, the model is able to reduce 82 data points down to five fit parameters. The fit-derived heat of combustion has a 96% correlation with the calculated heat of combustion but has a slope of 0.49 suggesting that only half of the theoretical heat of combustion is realized. Initial temperature is not a good discriminator of detonation events but heat of combustion holds promise as a potential variable for event classification. This model and corresponding analyses might improve the ability of sensing platforms to identify explosive types and sources.

Gordon, J. Motos

46

Micro-blast waves using detonation transmission tubing  

NASA Astrophysics Data System (ADS)

Micro-blast waves emerging from the open end of a detonation transmission tube were experimentally visualized in this study. A commercially available detonation transmission tube was used (Nonel tube, M/s Dyno Nobel, Sweden), which is a small diameter tube coated with a thin layer of explosive mixture (HMX + traces of Al) on its inner side. The typical explosive loading for this tube is of the order of 18 mg/m of tube length. The blast wave was visualized using a high speed digital camera (frame rate 1 MHz) to acquire time-resolved schlieren images of the resulting flow field. The visualization studies were complemented by computational fluid dynamic simulations. An analysis of the schlieren images showed that although the blast wave appears to be spherical, it propagates faster along the tube axis than along a direction perpendicular to the tube axis. Additionally, CFD analysis revealed the presence of a barrel shock and Mach disc, showing structures that are typical of an underexpanded jet. A theory in use for centered large-scale explosions of intermediate strength (10 < ? {p}/{p}_0 ? 0.02) gave good agreement with the blast trajectory along the tube axis. The energy of these micro-blast waves was found to be 1.25 ± 0.94 J and the average TNT equivalent was found to be 0.3. The repeatability in generating these micro-blast waves using the Nonel tube was very good (± 2 %) and this opens up the possibility of using this device for studying some of the phenomena associated with muzzle blasts in the near future.

Samuelraj, I. Obed; Jagadeesh, G.; Kontis, K.

2013-07-01

47

Application of detonation wave theory to subcritical vapor explosions  

SciTech Connect

Detonation wave theory was applied to the physical process of a vapor explosion. Initially, the experimental observations using hot water as the fuel and saturated refrigerant liquid as the coolant were analyzed with this technique. These tests are notable since peak explosion pressures were far below the critical pressure of the coolant. From the analysis, the volume fractions of the coolant vapor and the volume ratio of the two liquids prior to the explosion were estimated from the measured peak explosion pressures and associated explosion propagation velocities under the assumption that the process was steady and one-dimensional. Complete Hugoniot curves were constructed, and the detonation condition was initially determined under the assumption that flow velocity behind the shock was equal to the mixture sound speed. This assumption was checked with the tangency condition between the Rayleigh line and Hugoniot curve at the Chapman-Jouguet point, as well as the existence of a minimum in the entropy change across the shock wave. The point of minimum entropy showed good agreement with the graphical tangency point, but was slightly different than the sound speed criteria in pressure (<2%) with a larger difference in propagation speed (50%). This discrepancy between the three criteria becomes insignificant as the explosion pressure rises. This is demonstrated by examining a tin-water explosion experiment. This technique appears to be a useful tool to estimate initial conditions for subcritical vapor explosions.

Tibkin, L.; El-Beshbeeshy, M.; Bonazza, R.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

1995-07-01

48

Rotating Detonation Wave Propulsion: Experimental Challenges, Modeling, and Engine Concepts (Invited)  

E-print Network

Rotating Detonation Wave Propulsion: Experimental Challenges, Modeling, and Engine Concepts THE primary form of chemical energy conversion for jet and liquid rocket propulsion comes from energy release from detonations for propulsion or as a power source.1a This interest actually predates

Texas at Arlington, University of

49

Simulation of Laser Interaction with Ablative Plasma and ydrodynamic of Laser Supported Plasma(LSP)  

NASA Astrophysics Data System (ADS)

A general Godunov finite difference schemes-WENO(Weighted Essentially Non-Oscillatory) Schemes which have fifth-order accuracy was used to make a numerical calculation for 2-dimensional axis symmetrical laser-supported plasma flow field under laser ablated solid target. The models of the calculation of ionization degree of plasma and the interaction between laser beam and plasma and the simplified eos(equation of state) of plasma were considered in the simulation. The plasma field parameters during and after laser duration variation with time are also obtained. The simulation results show that the laser beam power was strong absorbed by plasma of target surface, and the velocity of LSD(Laser Supported Detonation) wave is half of ideal LSD value which derived from C-J detonation theory.

Huifeng, Tong; Zhiping, Tang

2011-06-01

50

Simulation of laser interaction with ablative plasma and hydrodynamic behavior of laser supported plasma  

SciTech Connect

When an intense laser beam irradiates on a solid target, ambient air ionizes and becomes plasma, while part of the target rises in temperature, melts, vaporizes, ionizes, and yet becomes plasma. A general Godunov finite difference scheme WENO (Weighted Essentially Non-Oscillatory Scheme) with fifth-order accuracy is used to simulate 2-dimensional axis symmetrical laser-supported plasma flow field in the process of laser ablation. The model of the calculation of ionization degree of plasma and the interaction between laser beam and plasma are considered in the simulation. The numerical simulations obtain the profiles of temperature, density, and velocity at different times which show the evolvement of the ablative plasma. The simulated results show that the laser energy is strongly absorbed by plasma on target surface and that the velocity of laser supported detonation (LSD) wave is half of the ideal LSD value derived from Chapman-Jouguet detonation theory.

Tong Huifeng; Yuan Hong [Institute of Fluid Physics, Chinese Academy of Engineering Physics, P.O. Box 919-101, Mianyang, Sichuan 621900 (China); Tang Zhiping [CAS Key Laboratory for Mechanical Behavior and Design of Materials, Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, Hefei 230026 (China)

2013-01-28

51

Analysis of Laser-Generated Impulse In An Airbreathing Pulsed Detonation Engine: Part 2  

Microsoft Academic Search

A detailed parametric study of airbreathing engine performance is carried out for the Lightcraft Technology Demonstrator (LTD), a 1.4-m diameter, 120-kg (dry mass) launch vehicle designed to become a microsatellite after reaching orbit. The LTD's pulsed detonation engine employs repetitively ignited, laser-supported detonation waves to develop thrust by expanding high pressure blast waves over an annular, interior shroud surface. This

Jacques C. Richard; Leik N. Myrabo

2005-01-01

52

Analysis of Laser-Generated Impulse In An Airbreathing Pulsed Detonation Engine: Part 2  

Microsoft Academic Search

A detailed parametric study of airbreathing engine performance is carried out for the Lightcraft Technology Demonstrator (LTD), a 1.4-m diameter, 120-kg (dry mass) launch vehicle designed to become a microsatellite after reaching orbit. The LTD’s pulsed detonation engine employs repetitively ignited, laser-supported detonation waves to develop thrust by expanding high pressure blast waves over an annular, interior shroud surface. This

Jacques C. Richard; Leik N. Myrabo

2005-01-01

53

The chemical-gas dynamic mechanisms of pulsating detonation wave instability  

Microsoft Academic Search

The chemical-gas dynamic mechanisms behind the instability and failure of a one- dimensional pulsating detonation wave driven by a three-step chain-branching reac- tion are revealed by direct numerical simulation. Two types of pulsating instability observed experimentally are explained. The first involves regular oscillations of the detonation front, where the instability is driven by low-frequency finite-amplitude compression and expansion waves in

Ashwani K. Kapila; J. J. Quirk

1999-01-01

54

Effect of reaction order on stability of planar detonation waves  

NASA Astrophysics Data System (ADS)

We examine the multi-dimensional linear and non-linear stability of planar detonation waves for one-step Arrhenius rate with arbitrary reaction order. A normal mode analysis with an iterative shooting method is used in linear stability. Results show that the effect of decreasing the reaction order is roughly equivalent to increasing the activation energy, or decreasing the heat release and overdrive. Both the one- and two-dimensional linear stability spectra consist of a larger number of unstable modes at lower reaction order. Bifurcation to non-oscillatory modes occurs at slightly lower activation energy or higher heat release and overdrive for lower reaction order. Thus overall, a lower reaction order results in more unstable waves. Numerical simulations, using a Weighted Essentially Non-Oscillatory scheme, show that activation energy has a stronger effect on cell regularity than the reaction order. It has been suggested that a relationship may exist between transverse wavelength from multi-dimensional linear stability analysis and cell sizes. Our computations confirm previous numerical results that show that the most unstable transverse wavelengths from linear stability analysis are comparable with the minimum channel width in which one full cell is observed in numerical simulations. Wider computations show that cells, which appear regular and periodic in narrow channel computations, become irregular. The average cell size approaches a consistent limit corresponding to an even larger size.

Liang, Z.; Khastoo, B.; Bauwens, L.

2005-02-01

55

A study on planar blast waves initiated by gaseous detonations. I - Estimation of initiation energy  

NASA Astrophysics Data System (ADS)

An experimental study has been made of the initiation of planar blast waves by gaseous detonations. A gaseous detonation initiated by a DDT process is submitted into a long tube filled with air at various initial pressures. The measurement of the decay process of a produced shock wave indicates that it can be treated as a 'plane source' blast wave, although there exists a secondary shock wave, which may be a detonation wave reflected on an end wall of a driver tube, behind the blast wave front. As a result, the decay of a propagation Mach number and a peak overpressure of the wave front as a function of a distance from the initiation source and the initial pressure of the medium are described by the quasi-similar theory of the idealized plane source blast wave. Comparing the experimental results with the theory leads to the estimation of an initiation energy of the blast wave. The initiation energies of oxyhydrogen detonations for three different mixture strengths, three different initial pressures, and two different sizes of the driver tube are estimated to show that about 30-40 percent of the chemical energy contained initially in the driver tube is used to initiate the blast wave.

Ohyagi, S.; Yoshihashi, T.; Harigaya, Y.

56

WAVE IMPLOSION AS AN INITIATION MECHANISM FOR PULSE DETONATION ENGINES  

Microsoft Academic Search

A device has been developed which uses shock focusing to enhance the transmission e-ciency of an initiator tube when used with pulse detonation engines. The initiator is capable of initiating detonations in ethylene-air and propane-air mixtures using less initiator fuel than is used in a conventional initiator tube. This toroidal initiator uses a single spark and an array of small-diameter

S. I. Jackson; M. P. Grunthaner; J. E. Shepherd

57

Damage in low alloy steel produced by sweeping, interacting detonation waves  

NASA Astrophysics Data System (ADS)

Detonation waves that sweep along the surface of a metal plate induce reduced pressure and enhanced shear, relative to the same detonation at normal incidence. Detonation waves at intermediate obliquity impress intermediate combined stress states. Release waves from the free surfaces may enter into play and contribute to the damage. Initiation of explosive at discrete points produces strong pressure, density, and velocity gradients in the gaseous explosive products in areas where the waves collide, are impressed in an adjacent metal, causing similar stress gradients within the metal that often leading to intense damage. In this work, we investigate damage generated in AISI 4130 steel by the combined effects of oblique drive and interacting detonation waves. The experimental data consist of multipoint velocimetry points probing the free surface in regions loaded by interacting detonation waves and regions between the interactions. Metallography on recovered plate records the plastic flow and damage correlated with the velocimetry data. Spall is indicated in most regions, but not some, and the alpha-epsilon stress-induced phase transformation appears in most regions, but not all.

Hull, L.; Gray, G.; Faulkner, J.; Briggs, M.

2014-05-01

58

Modeling two-dimensional shock initiation and detonation-wave phenomena in PBX 9404 and LX-17  

SciTech Connect

The ignition and growth concept of reactive flow in heterogeneous solid explosives is incorporated into a two-dimensional, finite element, Lagrangian code and used to model shock initiation and detonation wave propagation experiments on PBX 9404 and LX-17. The failure radii and corner turning abilities of detonating PBX 9404 and LX-17 are calculated. Two-dimensional shock initiation experiments on LX-17 which produce both failing and diverging detonation waves are accurately simulated.

Tarver, C.M.; Hallquist, J.O.

1981-05-15

59

Atomistic Studies of Shock-Wave and Detonation Phenomena in Energetic Materials  

NASA Astrophysics Data System (ADS)

The major goal of this PhD project is to investigate the fundamental properties of energetic materials, including their atomic and electronic structures, as well as mechanical properties, and relate these to the fundamental mechanisms of shock wave and detonation propagation using state-of-the-art simulation methods. The first part of this PhD project was aimed at the investigation of static properties of energetic materials (EMs) with specific focus on 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). The major goal was to calculate the isotropic and anisotropic equations of state for TATB within a range of compressions not accessible to experiment, and to make predictions of anisotropic sensitivity along various crystallographic directions. The second part of this PhD project was devoted to applications of a novel atomic-scale simulation method, referred to as the moving window molecular dynamics (MW-MD) technique, to study the fundamental mechanisms of condensed-phase detonation. Because shock wave is a leading part of the detonation wave, MW-MD was applied to demonstrate its effectiveness in resolving fast non-equilibrium processes taking place behind the shock-wave front during shock-induced solid-liquid phase transitions in crystalline aluminum. Next, MW-MD was used to investigate the fundamental mechanisms of detonation propagation in condensed energetic materials. Due to the chemical complexity of real EMs, a simplified AB model of a prototypical energetic material was used. The AB interatomic potential, which describes chemical bonds, as well as chemical reactions between atoms A and B in an AB solid, was modified to investigate the mechanism of the detonation wave propagation with different reactive activation barriers. The speed of the shock or detonation wave, which is an input parameter of MW-MD, was determined by locating the Chapman-Jouguet point along the reactive Hugoniot, which was simulated using the constant number of particles, volume, and temperature (NVT) ensemble in MD. Finally, the detonation wave structure was investigated as a function of activation barrier for the chemical reaction AB+B ? A+ BB. Different regimes of detonation propagation including 1-D laminar, 2-D cellular, and 3-D spinning and turbulent detonation regimes were identified.

Budzevich, Mikalai M.

2011-07-01

60

Critical diameter for the transmission of a detonation wave into a porous medium  

SciTech Connect

An experimental investigation has been undertaken to elucidate the existence of a critical diameter for the transmission of gaseous detonation into a porous medium. A Chapman-Jouguet (CJ) detonation is first established in a tube and allowed to transmit through an orifice plate into a porous medium comprised of inert spheres of equal diameter. It is found that detonation can successfully transmit past the orifice for diameters much smaller than the normal critical diameter (d{sub c}) of the mixture. An immediate transition from detonation to quasi-detonation normally takes place upon wave entry in the porous medium. Failure of detonation is observed to take place downstream of the orifice in the near-limit regime and is followed by deflagration to detonation transition (DDT) within the porous medium. Wave velocities in the porous medium are found to be identical to the corresponding values measured for direct transmission (without an orifice). For subcritical conditions, there is complete quenching of combustion in the pores. The critical composition (lean and rich) for mixtures with high activation energy is found to be practically the same as the propagation limits in the porous medium without an orifice. This indicates that the phenomenon is governed by the smallest physical dimension of the pore size, and thus a local failure mechanism exists. In mixtures highly diluted with argon, i.e., (C{sub 2}H{sub 2}-O{sub 2}) + 75% Ar, which have, a lower activation energy and for which the ``d{sub c} = 13{lambda}`` correlation (where {lambda} is the cell size) is known to break down, the critical composition appears to depend on the orifice diameter. The orifice now introduces a larger controlling length scale at the limits compared to the pore size, indicating that a global failure mechanism may prevail for such mixtures. Present findings are consistent with a local and global failure mechanism for normal detonation failure recently proposed by Lee.

Makris, A.; Oh, T.J.; Lee, J.H.S.; Knystautas, R. [McGill Univ., Montreal, Quebec (Canada)

1994-12-31

61

A Runge-Kutta Discontinuous Galerkin Method for Detonation Wave Simulation  

NASA Astrophysics Data System (ADS)

We apply a Runge-Kutta discontinuous Galerkin (RKDG) method to numerical solution of the reactive Euler equations. In order to keep conservation naturally, Taylor basis functions are utilized. We construct a new Taylor basis function which has smaller numerical error than previous Taylor basis function when the TVD limiter is used. The program is written with MPI for parallel computation. Numerical results of two-dimensional unstable detonation waves demonstrate that the resulting RKDG method performs well in resolving detonation wave structures. Load imbalance due to different stiffness in different subzones is discussed.

Yuan, L.; Zhang, L.

2011-09-01

62

Experimental Investigation of Heterogeneous HE Decomposition Mechanism in Detonation Wave Front  

NASA Astrophysics Data System (ADS)

The mechanism of decomposition of heterogeneous HE in hot spots is considered. Experimental investigations have shown that the main reason of formation of locally heated areas is the existance high-velocity microjets, which penetrate HE layers laying ahead. Chemical reaction, thus, can begin in hot spots already before detonation wave arrival. Different structures of detonation wave and different profiles of particle velocity in the chemical reaction zone can be explained by jets penetration. There is also discussion on the relation of von Neumann spike and Chapman-Jouguet state for high-density condensed HE.

Fedorov, A. V.

2002-07-01

63

Exploratory Study of Conductivity in Detonation Waves D. R. Wilson,  

E-print Network

MSE-TA, Inc., Butte, MT 59702 Shock tube experiments were performed to measure the conductivity, a better understanding of the process that cou- ples the electromagnetic field to the high enthalpy, high-pressure plasmas in a pulsed mode, single-shot experiments were performed using a detonation-driven shock tube

Texas at Arlington, University of

64

The Universal Role of Tubulence in the Propagation of Strong Shocks and Detonation Waves  

NASA Astrophysics Data System (ADS)

The passage of a strong shock wave usually results in irreversible physical and chemical changes in the medium. If the chemical reactions are sufficiently exothermic, the shock wave can be self-propagating, i.e., sustained by the chemical energy release via the expansion work of the reaction products. Although shocks and detonations can be globally stable and propagate at constant velocities (in the direction of motion), their structure may be highly unstable and exhibit large hydrodynamic fluctuations, i.e., turbulence. Recent investigations on plastic deformation of polycrystalline material behind shock waves have revealed particle velocity dispersion at the mesoscopic level, a result of vortical rotational motion similar to that of turbulent fluid flows at high Reynolds number.1 Strong ionizing shocks in noble gases2, as well as dissociating shock waves in carbon dioxide,3 also demonstrate a turbulent density fluctuation in the non-equilibrium shock transition zone. Perhaps the most thoroughly investigated unstable structure is that of detonation waves in gaseous explosives.4 Detonation waves in liquid explosives such as nitromethane also take on similar unstable structure as gaseous detonations.5 There are also indications that detonations in solid explosives have a similar unsteady structure under certain conditions. Thus, it appears that it is more of a rule than an exception that the structure of strong shocks and detonations are unstable and exhibit turbulent-like fluctuations as improved diagnostics now permit us to look more closely at the meso- and micro-levels. Increasing attention is now devoted to the understanding of the shock waves at the micro-scale level in recent years. This is motivated by the need to formulate physical and chemical models that contain the correct physics capable of describing quantitatively the shock transition process. It should be noted that, in spite of its unstable 3-D structure, the steady 1-D conservation laws (in the direction of propagation) apply across the shock transition zone if the downstream equilibrium plane is taken far enough away to ensure the decay of the turbulent fluctuations. Thus, the Hugoniot properties of one-dimensional propagation of shock and detonation waves remain valid. However, the conservation laws do not describe the important propagation mechanisms (i.e., the physical and chemical processes that effect the transition from initial to the final state) in the wave structure. Since gaseous detonations enjoy the advantage of being able to be observed experimentally in great detail, its complex turbulent structure is now quite well established. Furthermore, the equation of state for perfect gases is well known and the chemistry of most gas phase reactions is also sufficiently understood quantitatively to permit detailed numerical simulation of the complex detonation structure. Thus, a good database of information exists for gaseous detonation, and in this paper we shall explore the turbulent structure of gaseous detonation with the aim of answering the question as to "why nature prefers to evoke such a complicated manner to effect its propagation." We will then attempt to generalize the discussion to the "terra incognita" of condensed phase materials where the structure is much less understood. 1. Meshcheryakov, Yu.I., and Atroshenko, S.A., Izv. Vyssh. Uchebn. Zaved. Fiz., 4, 105-123 (1992). 2. Glass, I.I, and Liu, W.S., J. Fluid Mech., 84(1), 55-77 (1978). 3. Griffiths, R.W., Sanderman, R.J., and Hornung, H.G., J. Phys. D., 8, 1681-1691 (1975). 4. Lee, J.H.S., Ann. Rev. Fluid Mech., 16, 311-336 (1984). 5. Mallory, H.D., J. Appl. Physics, 38, 5302-5306 (1967).

Lee, John H.

2001-06-01

65

On the existence of fast strong and fast weak ionizing detonation waves in magnetohydrodynamics  

Microsoft Academic Search

The existence of structure for ionizing fast-strong and fast-weak detonation waves in magnetohydrodynamics are proved. The reactions are assumed to be one step exothermic reactions with a natural discontinuous reaction rate function. The problem is studied for a general gas, considering some general thermodynamics rules which described by a fairly mild set of hypotheses. The uniqueness and nonuniqueness of structure

A. Aghajani; Y. Farjami; M. Hesaaraki

2009-01-01

66

Critical deflagration waves leading to detonation onset under different boundary conditions  

NASA Astrophysics Data System (ADS)

High-speed turbulent critical deflagration waves before detonation onset in H2–air mixture propagated into a square cross section channel, which was assembled of optional rigid rough, rigid smooth, or flexible walls. The corresponding propagation characteristic and the influence of the wall boundaries on the propagation were investigated via high-speed shadowgraph and a high-frequency pressure sampling system. As a comprehensive supplement to the different walls effect investigation, the effect of porous absorbing walls on the detonation propagation was also investigated via smoke foils and the high-frequency pressure sampling system. Results are as follows. In the critical deflagration stage, the leading shock and the closely following turbulent flame front travel at a speed of nearly half the CJ detonation velocity. In the preheated zone, a zonary flame arises from the overlapping part of the boundary layer and the pressure waves, and then merges into the mainstream flame. Among these wall boundary conditions, the rigid rough wall plays a most positive role in the formation of the zonary flame and thus accelerates the transition of the deflagration to detonation (DDT), which is due to the boost of the boundary layer growth and the pressure wave reflection. Even though the flexible wall is not conducive to the pressure wave reflection, it brings out a faster boundary layer growth, which plays a more significant role in the zonary flame formation. Additionally, the porous absorbing wall absorbs the transverse wave and yields detonation decay and velocity deficit. After the absorbing wall, below some low initial pressure conditions, no re-initiation occurs and the deflagration propagates in critical deflagration for a relatively long distance. Project supported by the National Natural Science Foundation of China (Grant No. 51206182).

Lin, Wei; Zhou, Jin; Fan, Xiao-Hua; Lin, Zhi-Yong

2015-01-01

67

Existence of steady-state fuel-coolant thermal detonation waves  

Microsoft Academic Search

The possibility of a steady-state Chapman-Jouguet thermal detonation wave propagating through an initially coarse mixture of molten fuel and coolant in the course of a nuclear reactor accident is examined. The postulated mechanism is the breakup of single drops of heavy, hot liquid immersed in a vaporizable cold liquid (tin-water, or UO-sodium) due to passage of a shock wave, with

S. G. Bankoff; J. H. Jo

1976-01-01

68

Explosively generated shock wave processing of metal powders by instrumented detonics  

NASA Astrophysics Data System (ADS)

The highest pressures generated by dynamic processes resulting either from high velocity impact or by spontaneous release of high energy rate substances in direct contact with a metal find superior applications over normal mechanical means. The special feature of explosive loading to the powder materials over traditional methods is its controlled detonation pressure which directly transmits shock energy to the materials which remain entrapped inside powder resulting into several micro-structural changes and hence improved mechanical properties. superalloy powders have been compacted nearer to the theoretical density by shock wave consolidation. In a single experimental set-up, compaction of metal powder and measurement of detonation velocity have been achieved successfully by using instrumented detonics. The thrust on the work is to obtain uniform, crack-free and fracture-less compacts of superalloys having intact crystalline structure as has been examined from FE-SEM, XRD and mechanical studies. Shock wave processing is an emerging technique and receiving much attention of the materials scientists and engineers owing to its excellent advantages over traditional metallurgical methods due to short processing time, scaleup advantage and controlled detonation pressure.

Sharma, A. D.; Sharma, A. K.; Thakur, N.

2013-06-01

69

Deflagration-to-detonation transition by amplification of acoustic waves in type Ia supernovae  

NASA Astrophysics Data System (ADS)

Aims: We study a new mechanism for deflagration-to-detonation transition in thermonuclear supernovae (SNe Ia), based on the formation of shocks by amplification of sound waves in the steep density gradients of white dwarfs envelopes. We characterise, in terms of wavelength and amplitude, the perturbations which will ignite a detonation after their amplification. Methods: This study was performed using the well tested HERACLES code, a conservative hydrodynamical code, validated in the present specific application by an analytical description of the propagation of sound waves in white dwarfs. Thermonuclear combustion of the carbon oxygen fuel was treated with the ?-chain nuclear reactions network. Results: In planar geometry we found the critical parameter to be the height of shock formation. When it occurs in the inner dense regions (? > 106 g cm-3) detonation is inevitable but can take an arbitrarily long time. We found that ignition can be achieved for perturbation as low as Mach number: M ~ 0.005, with heating times compatible with typical explosion time scale (a few seconds). On the opposite no ignition occurs when shocks initiated by small amplitude or large wavelength form further away in less dense regions. We show finally that ignition is also achieved in a spherical self-gravitating spherical model of cold C+O white dwarf of 1.430 M?, but due to the spherical damping of sound waves it necessitates stronger perturbation (M ~ 0.02). Small perturbations (M ~ 0.003) could still trigger detonation if a small helium layer is considered. In the context of SNe Ia, one has to consider further the initial expansion of the white dwarf, triggered by the deflagration, prior to the transition to detonation. As the star expands, gradients get flatter and ignition requires increasingly strong perturbations.

Charignon, C.; Chièze, J.-P.

2013-02-01

70

1899-1909: Key Years for Shock Wave and Detonation Theory  

NASA Astrophysics Data System (ADS)

One century ago, in 1909, finished one of the most creative decade for the progress of shock wave and detonation understanding. Before these years, many experiments were undetaken and analyzed by Berthelot, Mallard, Vieille, Le Châtellier and Dixon, especially about reactive gaseous mixtures. In 1899, Chapman provided the basis of what is called now the Chapman- Jouguet theory. During the following years, an unusual high number papers were published by different authors (Jouguet, Hadamard, Crussard, Duhem, Dixon and the hungarish Zemplen...) who yielded important contributions to the understanding of shock wave and detonation propagation. They tried to precise the former knowledge and to extend it to real geometries and to real materials. These years finished in 1909 with Duhem's paper which gathered some properties concerning real materials. After these years, the number of papers about shock waves and detonation strongly decreased. The main questions were raised, some of them were solved and the others had to wait up to several decades to be answered, by Von Neumann, Bethe, Zel'dovitch and others. Then Jouguet focused on deflagration, others retired or moved to other topics. We have collected an exhaustive bibliography. If most of these papers are now historical, some formulae or ideas like the forgotten concept of ``quasi-wave,'' with finite thickness, has a renewed interest for numerical or modern studies.

Heuze, Olivier

2009-06-01

71

Detonation wave profiles measured in plastic bonded explosives using 1550 nm photon doppler velocimetry (PDV)  

SciTech Connect

We present detonation wave profiles measured in two TATB based explosives and two HMX based explosives. Profiles were measured at the interface of the explosive and a Lithium-Fluoride (LiF) window using 1550 nm Photon Doppler Velocimetry (PDV). Planar detonations were produced by impacting the explosive with a projectile launched in a gas-gun. The impact state was varied to produce varied distance to detonation, and therefore varied support of the Taylor wave following the Chapman-Jouget (CJ) or sonic state. Profiles from experiments with different support should be the same between the Von-Neumann (VN) spike and CJ state and different thereafter. Comparison of profiles with differing support, therefore, allows us to estimate reaction zone lengths. For the TATB based explosive, a reaction zone length of {approx} 3.9 mm, 500 ns was measured in EDC-35, and a reaction zone length of {approx} 6.3 mm, 800 ns was measured in PBX 9502 pre-cooled to -55 C. The respective VN spike state was 2.25 {+-} 0.05 km/s in EDC-35 and 2.4 {+-} 0.1 km/s in the cooled PBX 9502. We do not believe we have resolved either the VN spike state (> 2.6 km/s) nor the reaction zone length (<< 50 ns) in the HMX based explosives.

Gustavsen, Richard L [Los Alamos National Laboratory; Bartram, Brian D [Los Alamos National Laboratory; Sanchez, Nathaniel (nate) J [Los Alamos National Laboratory

2009-01-01

72

Modelling detonation waves in condensed energetic materials: multiphase CJ conditions and multidimensional computations  

NASA Astrophysics Data System (ADS)

A hyperbolic multiphase flow model with a single pressure and a single velocity but several temperatures is proposed to deal with the detonation dynamics of condensed energetic materials. Temperature non-equilibrium effects are mandatory in order to deal with wave propagation (shocks, detonations) in heterogeneous mixtures. The model is obtained as the asymptotic limit of a total non-equilibrium multiphase flow model in the limit of stiff mechanical relaxation only (Kapila et al. in Phys Fluids 13:3002-3024, 2001). Special attention is given to mass transfer modelling, that is obtained on the basis of entropy production analysis in each phase and in the system (Saurel et al. in J Fluid Mech 607:313-350, 2008). With the help of the shock relations given in Saurel et al. (Shock Waves 16:209-232, 2007) the model is closed and provides a generalized ZND formulation for condensed energetic materials. In particular, generalized CJ conditions are obtained. They are based on a balance between the chemical reaction energy release and internal heat exchanges among phases. Moreover, the sound speed that appears at sonic surface corresponds to the one of Wood (A textbook of sound, G. Bell and Sons LTD, London, 1930) that presents a non-monotonic behaviour versus volume fraction. Therefore, non-conventional reaction zone structure is observed. When heat exchanges are absent, the conventional ZND model with conventional CJ conditions is recovered. When heat exchanges are involved interesting features are observed. The flow behaviour presents similarities with non ideal detonations (Wood and Kirkwood in J Chem Phys 22:1920-1924, 1950) and pathological detonations (Von Neuman in Theory of detonation waves, 1942; Guenoche et al. in AIAA Prog Astron Aeronaut 75: 387-407, 1981). It also present non-conventional behaviour with detonation velocity eventually greater than the CJ one. Multidimensional resolution of the corresponding model is then addressed. This poses serious difficulties related to the presence of material interfaces and shock propagation in multiphase mixtures. The first issue is solved by an extension of the method derived in Saurel et al. (J Comput Phys 228(5):1678-1712, 2009) in the presence of heat and mass transfers. The second issue poses the difficult mathematical question of numerical approximation of non-conservative systems in the presence of shocks associated to the physical question of energy partition among phases for a multiphase shock. A novel approach is used, based on extra evolution equations used to retain the information of the material initial state. This method insures convergence in the post-shock state. Thanks to these various theoretical and numerical ingredients, one-dimensional and multidimensional unsteady detonation waves computations are done, eventually in the presence of material interfaces. Convergence of the numerical hyperbolic solver against ZND multiphase solution is reached. Material interfaces, shocks, detonations are solved with a unified formulation where the same equations are solved everywhere with the same numerical scheme.

Petitpas, F.; Saurel, Richard; Franquet, E.; Chinnayya, A.

2009-10-01

73

Pulse detonation engine test system  

Microsoft Academic Search

A test system of pulse detonation engine, based on PCI-6115 Data Acquisition Card and Front Integrated Instrument, Access databases and NI-Measurement Studio programming design suites in Windows. This test system is used to record the test data of pulse detonation engine and research the properties of detonation wave. Plenty of test data of pulse detonation engine which was recorded by

Xiaoming He; Jiankang Lu

2010-01-01

74

The structure and evolution of galacto-detonation waves - Some analytic results in sequential star formation models of spiral galaxies  

NASA Technical Reports Server (NTRS)

Waves of star formation in a uniform, differentially rotating disk galaxy are treated analytically as a propagating detonation wave front. It is shown, that if single solitary waves could be excited, they would evolve asymptotically to one of two stable spiral forms, each of which rotates with a fixed pattern speed. Simple numerical solutions confirm these results. However, the pattern of waves that develop naturally from an initially localized disturbance is more complex and dies out within a few rotation periods. These results suggest a conclusive observational test for deciding whether sequential star formation is an important determinant of spiral structure in some class of galaxies.

Cowie, L. L.; Rybicki, G. B.

1982-01-01

75

Steady One-Dimensional Detonations  

NASA Astrophysics Data System (ADS)

While treatments of detonation wave propagation using control volume analysis, such as the Chapman-Jouguet (CJ) detonation solution presented in the prior chapter, are very successful in predicting the steady-state, equilibrium properties of detonations, they provide no information about the limits of detonation propagation or the dynamics of detonation waves. Addressing these issues necessitates investigating the structure of the detonation front. To illustrate this point, consider an extremely dilute concentration of fuel in air (e.g., 0.1% of methane in air by volume). If this mixture is entered into a thermochemical equilibrium code, a unique equilibrium CJ detonation solution will be generated. In practice, however, such a dilute mixture is highly unlikely to be able to support detonation wave propagation, since the low post-shock temperatures from the weak leading shock front would result in very slow reaction rates or no perceptible reaction at all.

Higgins, Andrew

76

Portable fiber optic coupled doppler interferometer system for detonation and shock wave diagnostics  

SciTech Connect

Testing and analysis of shock wave characteristics such as produced by detonators and ground shock propagation frequently require a method of measuring velocity and displacement of the surface of interest. One method of measurement is doppler interferometry. The VISAR (Velocity Interferometer System for Any Reflector) uses doppler interferometry and has pined wide acceptance as the preferred tool for shock measurement. An important asset of VISAR is that it measures velocity and displacement non intrusively. The conventional VISAR is not well suited for portability because of its sensitive components, large power and cooling requirements, and hazardous laser beam. A new VISAR using the latest technology in solid state lasers and detectors has been developed and tested. To further enhance this system`s versatility, the unit is fiber optic coupled which allows remote testing, permitting the VISAR to be placed over a kilometer away from the target being measured. Because the laser light is contained in the fiber optic, operation of the system around personnel is far less hazardous. A software package for data reduction has also been developed for use with a personal computer. These new advances have produced a very versatile system with full portability which can be totally powered by batteries or a small generator. This paper describes the solid state VISAR and its peripheral components, fiber optic coupling methods and the fiber optic coupled sensors used for sending and receiving laser radiation.

Fleming, K.J.

1993-03-01

77

One-Dimensional Shock and Detonation Wave Simulator Philip Caplan Dominic LeBlanc Adam Sirignano Amanda Starr Supervisor: Prof. Andrew J. Higgins April 2012  

E-print Network

(yellow) . Next, a runaway train (red) crashes into the first car. Since the train had a lot of energy is transmitted via their magnetic fields. What are shock & detonation waves? Imagine a line of parked train cars, this crash continues down the line of cars and can be thought of as a propagating shock wave. Why a shock

Peraire, Jaime

78

Plane thermonuclear detonation waves initiated by proton beams and quasi-one-dimensional model of fast ignition  

E-print Network

The one-dimensional (1D) problem on bilatiral irradiation by proton beams of the plane layer of condensed DT mixture with length $2H$ and density $\\rho_0 \\leqslant 100\\rho_s$, where $\\rho_s$ is the fuel solid-state density at atmospheric pressure and temperature of 4 K, is considered. The proton kinetic energy is 1 MeV, the beam intensity is $10^{19}$ W/cm$^2$ and duration is 50 ps. A mathematical model is based on the one-fluid two-temperature hydrodynamics with a wide-range equation of state of the fuel, electron and ion heat conduction, DT fusion reaction kinetics, self-radiation of plasma and plasma heating by alpha-particles. If the ignition occurs, a plane detonation wave, which is adjacent to the front of the rarefaction wave, appears. Upon reflection of this detonation wave from the symmetry plane, the flow with the linear velocity profile along the spatial variable $x$ and with a weak dependence of the thermodynamic functions of $x$ occurs. An appropriate solution of the equations of hydrodynamics is...

Charakhch'yan, Alexander A

2014-01-01

79

MULTIPLE CYCLE DETONATION EXPERIMENTS DURING THE DEVELOPMENT OF A PULSE DETONATION ENGINE  

Microsoft Academic Search

Multiple cycle detonation tube experiments performed to support the development of a prototype, hydrogen faded, pulse detonation engine (PDE) ate described. Measured parameters include pressure histories at various wall locations along the length of the detonation tube, thrust force histories, luminosity histories, detonation wave velocities, delivered impulses, and specific impulses. Two failure modes were encountered during some of these experiments:

Michael J. Aarnio; John B. Hinkey; Thomas R. A. Bussing

80

Numerical studies of pre-detonator ignition of pulse detonation engine  

Microsoft Academic Search

Two-dimensional numerical simulations of pre-detonator ignition of pulse detonation engine were performed. The pre-detonators are installed at the closed-end of the main detonation tube in two different ways: either in parallel with or perpendicular to the main detonation tube axis. Studies indicate that the perpendicular arrangement is better than the parallel layout because the reflected shock waves play an important

J. P. Wang; Y. F. Liu; T. W. Li

2005-01-01

81

Pulse detonation engines: Technical approaches  

Microsoft Academic Search

The paper contains analysis of the problems preventing from wide use of pulse detonation engines (PDE), and provides suggestions to overcome those problems. In particular, the results of theoretical investigations of basic operating cycle in PDE—deflagration-to-detonation transition (DDT) processes in combustible gaseous mixtures and transmission of detonation into large chambers—are presented. The paper investigates the effect of implosion shock waves

V. F. Nikitin; V. R. Dushin; Y. G. Phylippov; J. C. Legros

2009-01-01

82

Molecular dynamics and kinetic study of carbon coagulation in the release wave of detonation products.  

PubMed

We present a combined molecular dynamics and kinetic study of a carbon cluster aggregation process in thermodynamic conditions relevant for the detonation products of oxygen deficient explosives. Molecular dynamics simulations with the LCBOPII potential under gigapascal pressure and high temperatures indicate that (i) the cluster motion in the detonation gas is compatible with Brownian diffusion and (ii) the coalescence probability is 100% for two clusters entering the interaction cutoff distance. We used these results for a subsequent kinetic study with the Smoluchowski model, with realistic models applied for the physical parameters such as viscosity and cluster size. We found that purely aggregational kinetics yield too fast clustering, with moderate influence of the model parameters. In agreement with previous studies, the introduction of surface reactivity through a simple kinetic model is necessary to approach the clustering time scales suggested by experiments (1000 atoms after 100 ns, 10 000 atoms after 1 ?s). However, these models fail to reach all experimental criteria simultaneously and more complex modelling of the surface process seems desirable to go beyond these current limitations. PMID:22380052

Chevrot, Guillaume; Sollier, Arnaud; Pineau, Nicolas

2012-02-28

83

Molecular dynamics and kinetic study of carbon coagulation in the release wave of detonation products  

NASA Astrophysics Data System (ADS)

We present a combined molecular dynamics and kinetic study of a carbon cluster aggregation process in thermodynamic conditions relevant for the detonation products of oxygen deficient explosives. Molecular dynamics simulations with the LCBOPII potential under gigapascal pressure and high temperatures indicate that (i) the cluster motion in the detonation gas is compatible with Brownian diffusion and (ii) the coalescence probability is 100% for two clusters entering the interaction cutoff distance. We used these results for a subsequent kinetic study with the Smoluchowski model, with realistic models applied for the physical parameters such as viscosity and cluster size. We found that purely aggregational kinetics yield too fast clustering, with moderate influence of the model parameters. In agreement with previous studies, the introduction of surface reactivity through a simple kinetic model is necessary to approach the clustering time scales suggested by experiments (1000 atoms after 100 ns, 10 000 atoms after 1 ?s). However, these models fail to reach all experimental criteria simultaneously and more complex modelling of the surface process seems desirable to go beyond these current limitations.

Chevrot, Guillaume; Sollier, Arnaud; Pineau, Nicolas

2012-02-01

84

On the Hydrodynamic Thickness of Cellular Detonations  

Microsoft Academic Search

The characterization of the detonation dynamic parameters (detonability limits, direct initiation energy, critical tube diameter,\\u000a etc.) requires a characteristic length scale for the detonation wave in the direction of propagation. However, most detonations\\u000a are unstable, their reaction zones are turbulent, and their structure departs significantly from the idealized one-dimensional\\u000a Zel'dovich-Von Neumann-Doring model. It is argued that the most suitable length

J. H. S. Lee; M. I. Radulescu

2005-01-01

85

A Simplified Analysis on a Pulse Detonation Engine Model  

Microsoft Academic Search

The performance of pulse detonation engines was analytically estimated by using a simple model. A pulse detonation engine was modeled as a straight tube. One end of the tube was closed and the other was open, and a detonation wave was ignited at the closed end. One cycle of the pulse-detonation-engine operation was divided into three phases: combustion, exhaust, and

Takuma Endo; Toshi Fujiwara

2005-01-01

86

Two phase detonation studies conducted in 1971  

NASA Technical Reports Server (NTRS)

A report is presented describing the research conducted on five phases: (1) ignition of fuel drops by a shock wave and passage of a shock wave over a burning drop, (2) the energy release pattern of a two-phase detonation with controlled drop sizes, (3) the attenuation of shock and detonation waves passing over an acoustic liner, (4) experimental and theoretical studies of film detonations, and (5) a simplified analytical model of a rotating two-phase detonation wave in a rocket motor.

Nicholls, J. A.

1972-01-01

87

Specific Features of Synthesis of Detonation Nanodiamonds  

Microsoft Academic Search

It is demonstrated that the Chapman-Jouguet parameters for high explosives used in nanodiamond synthesis are located in the region of liquid nanocarbon; therefore, the chemical reaction zone of the detonation wave involves formation of carbon nanodroplets, which are later crystallized into nanodiamonds on the segment of the isentrope of expansion of detonation products, passing through the region of stability of

V. V. Danilenko

2005-01-01

88

Carbon in detonations  

SciTech Connect

We review three principal results from a five year study of carbon and its properties in detonations and discuss the implications of these results to the behavior of explosives. We first present a new determination of the carbon melt line from release wave velocity measurements in the shocked state. We then outline a colloidal theory of carbon clustering which from diffusion limited coagulation predicts a slow energy release rate for the carbon chemistry. Finally, we show the results from the examination of recovered soot. Here we see support for the colloid theory and find the diamond phase of carbon. The main theme of this paper is that the carbon in detonation products is in the form of a colloidal suspension of carbon clusters which grow through diffusion limited collisions. Even the final state is not bulk graphite or diamond, but is a collection of small, less than 100 /angstrom/A, diamond and graphitic clusters. 23 refs., 4 figs.

Johnson, J.D.

1989-01-01

89

Numerical study on hypervelocity acceleration of flyer plates by overdriven detonation of high explosive  

Microsoft Academic Search

In most applications of explosives to flyer acceleration, the detonation of explosives is usually regarded as a steadily progressing wave phenomenon in which the pressure of the detonation products immediately behind the wave front is characterized by the so-called Chapman-Jouguet (C-J) pressure value. This type of detonation is therefore routinely referred to as the C-J detonation behavior and the detonation

Zhi-Yue Liu; Kubota Shiro; Itoh Shigeru

2001-01-01

90

Aluminum Particles–air Detonation at Elevated Pressures  

Microsoft Academic Search

The effect of initial pressure on aluminum particles–air detonation was experimentally investigated in a 13 m long, 80 mm diameter tube for 100 nm and 2 µm spherical particles. While the 100 nm Al–air detonation propagates at 1 atm initial pressure in the tube, transition to the 2 µm aluminum–air detonation occurs only when the initial pressure is increased to 2.5 atm. The detonation wave manifests itself in

F. Zhang; S. B. Murray; K. B. Gerrard

2006-01-01

91

Detonation Properties and Thermal Behavior of FOX7Based Explosives  

Microsoft Academic Search

Phlegmatized FOX-7 (1,1-diamino-2,2-dinitroethylene, DADNE) and mixtures with cyclotetramethylene tetranitramine (HMX) were prepared and their detonation properties (the detonation velocity, detonation pressure, acceleration ability, and detonation energy) were investigated. The sensitivity of these compositions to mechanical stimuli (friction, impact, and shock wave) were determined, and the thermal stability and compatibility of the components were tested. This work furthers the investigation into

W. A. Trzci?ski; S. Cudzi?o; Z. Chy?ek; L. Szyma?czyk

2013-01-01

92

Initiation of Gaseous Detonation by Conical Projectiles  

NASA Astrophysics Data System (ADS)

Initiation and stabilization of detonation by hypersonic conical projectiles launched into combustible gas mixtures is investigated. This phenomenon must be understood for the design and optimization of specific hypersonic propulsion devices, such as the oblique detonation wave engine and the ram accelerator. The criteria for detonation initiation by a projectile is also related to fundamental aspects of detonation research, such as the requirement for direct initiation of a detonation by a blast wave. Experimental results of this problem also offer useful references for validation of numerical and theoretical modeling. Projectiles with cone half angles varying from 15° to 60° were launched into stoichiometric mixtures of hydrogen/oxygen with 70% argon dilution at initial pressures between 10 and 200 kPa. The projectiles were launched from a combustion-driven gas gun at velocities up to 2.2 km/s (corresponding to 133% of the Chapman Jouguet velocity). Pictures of the flowfields generated by the projectiles were taken via Schlieren photography. Five combustion regimes were observed about the projectile ranging from prompt and delayed oblique detonation wave formation, combustion instabilities, a wave splitting, and an inert shock wave. Two types of transition from the prompt oblique detonation wave regime to the inert shock regime were observed. The first (the delayed oblique detonation wave regime) showed an inert shock attached to the tip of the projectile followed by a sharp kink at the onset of an oblique detonation wave; this regime occurred by decreasing the cone angle at high mixture pressures. The second (the combustion instabilities regime) exhibited large density gradients due to combustion ignition and quenching phenomena; this regime occurred by decreasing the mixture pressure at large cone angles. A number of theoretical models were considered to predict critical conditions for the initiation of oblique detonations. The Lee-Vasiljev model agreed qualitatively well with the experimental results for relatively blunt projectiles (cone half-angle larger than 35°) and low mixture pressures (lower than 100 kPa). The trend of the critical Damköhler number calculated along the projectile cone surface was similar to that of the experimental results for slender cones (cone half-angles lower 35°) and high mixture pressures (higher than 100 kPa). Steady 2D simulations of reacting flows over finite wedges using the method of characteristics with a one-step Arrhenius chemical reaction model reproduced the three regimes observed for direct initiation of a detonation: the subcritical, critical and supercritical regimes. It is shown that in order for a 2D wedge to be equivalent to the problem of blast initiation of a detonation (which is the essence of the Lee-Vasiljev model), the Mach number normal to the oblique shock needs to be greater than 50 and the wedge angle has to be smaller than 30°. Simulations of reacting flows over semi-infinite wedges and cones were validated with CFD results. Excellent agreement was reached between the angle of overdriven oblique detonations obtained from the simulations and those from a polar analysis. For wedge or cone angles equal or lower than the minimum angle for which an oblique detonation is attached (according to the polar analysis), a Chapman-Jouguet oblique detonation was initiated. In the conical configuration, the curvature around the cone axis allowed an oblique detonation to be self-sustained at an angle less than without the curvature effect. At larger activation energies, the initiation process of an oblique detonation wave at the tip of a semi-infinite wedge or cone was identified. Unsteady 2D computational simulations were also conducted and showed the cellular structure of an oblique detonation wave. Instabilities in the form of transverse shock waves along the oblique detonation front arise for large activation energies.

Verreault, Jimmy

93

Combustion and Gas Dynamics as Related to Pulse-Detonation Engine  

Microsoft Academic Search

Recent renewed interest in initiating detonation as a favorable combustion process prompted the authors to examine the method of calculation of the process of detonation of premixed hydro-carbon fuel-air mixture. As a prospective propulsive device, the unsteady inviscid flow field behind the detonation wave within a pulse detonation engine was also examined. Although the flow field can be explored through

W. L. CHOW; CHRIS YIANNA

94

Oxyhydrogen combustion and detonation driven shock tube  

NASA Astrophysics Data System (ADS)

The performance of combustion driver ignited by multi-spark plugs distributed along axial direction has been analysed and tested. An improved ignition method with three circumferential equidistributed ignitors at main diaphragm has been presented, by which the produced incident shock waves have higher repeatability, and better steadiness in the pressure, temperature and velocity fields of flow behind the incidence shock, and thus meets the requirements of aerodynamic experiment. The attachment of a damping section at the end of the driver can eliminate the high reflection pressure produced by detonation wave, and the backward detonation driver can be employed to generate high enthalpy and high density test flow. The incident shock wave produced by this method is well repeated and with weak attenuation. The reflection wave caused by the contracted section at the main diaphragm will weaken the unfavorable effect of rarefaction wave behind the detonation wave, which indicates that the forward detonation driver can be applied in the practice. For incident shock wave of identical strength, the initial pressure of the forward detonation driver is about 1 order of magnitude lower than that of backward detonation.

Hongru, Yu

1999-05-01

95

Preliminary Experimental Investigation on Detonation Initiation in the Ejector of a Pulse Detonation Rocket Engine  

NASA Astrophysics Data System (ADS)

A small pulse detonation rocket engine (PDRE) was used as a predetonator to initiate detonation in its ejector. The detonation products discharged from the PDRE was not only ignition source for the ejector but also primary flow which entrained air from environment into the ejector. Stoichiometric liquid kerosene and gaseous oxygen were used as reactants for the PDRE. While in the ejector injected liquid kerosene was used as fuel and entrained air was used as oxidizer. Reactants in the ejector were ignited by the detonation wave and products discharged from the PDRE. Detonation was successfully initiation in present experiments. It was found that flame propagation upstream at the entrance of the ejector was inevitable, which affected the detonation initiation process in the ejector. Disks with orifices were placed at the entrance of the ejector to weaken the flame propagation upstream effect, which would affect the air flow entraining process, but the results show it worked.

Yan, Yu; Fan, Wei; Mu, Yang

2012-12-01

96

Reactant jetting in unstable detonation  

NASA Astrophysics Data System (ADS)

We note the common existence of a supersonic jet structure locally embedded within a surrounding transonic flow field in the hitherto unrelated phenomena of unstable gaseous detonation and hypervelocity blunt body shock wave interaction. Extending prior results that demonstrate the consequences of reduced endothermic reaction rate for the supersonic jet fluid in the blunt body case, we provide an explanation for observations of locally reduced OH PLIF signal in images of the keystone reaction zone structure of weakly unstable detonations. Modeling these flow features as exothermically reacting jets with similarly reduced reaction rates, we demonstrate a mechanism for jetting of bulk pockets of unreacted fluid with potentially differing kinetic pathways into the region behind the primary detonation front of strongly unstable mixtures. We examine the impact of mono-atomic and diatomic diluents on transverse structure. The results yield insight into the mechanisms of transition and characteristic features of both weakly and strongly unstable mixtures.

Sanderson, S. R.; Austin, J. M.; Liang, Z.; Pintgen, F.; Shepherd, J. E.; Hornung, H. G.

2010-02-01

97

Internal Detonation Velocity Measurements Inside High Explosives  

SciTech Connect

In order to fully calibrate hydrocodes and dynamic chemistry burn models, initiation models and detonation models of high explosives, the ability to continuously measure the detonation velocity within an explosive is required. Progress on an embedded velocity diagnostic using a 125 micron diameter optical fiber containing a chirped fiber Bragg grating is reported. As the chirped fiber Bragg grating is consumed by the moving detonation wave, the physical length of the unconsumed Bragg grating is monitored with a fast InGaAs photodiode. Experimental details of the associated equipment and data in the form of continuous detonation velocity records within PBX-9502 are presented. This small diameter fiber sensor has the potential to measure internal detonation velocities on the order of 10 mm/{micro}sec along path lengths tens of millimeters long.

Benterou, J; Bennett, C V; Cole, G; Hare, D E; May, C; Udd, E

2009-01-16

98

Effect of Detonation through a Turbine Stage  

NASA Technical Reports Server (NTRS)

Pulse detonation engines (PDE) have been investigated as a more efficient means of propulsion due to its constant volume combustion rather than the more often used constant pressure combustion of other propulsion systems. It has been proposed that a hybrid PDE-gas turbine engine would be a feasible means of improving the efficiency of the typical constant pressure combustion gas turbine cycle. In this proposed system, multiple pulse detonation tubes would replace the conventional combustor. Also, some of the compressor stages may be removed due to the pressure rise gained across the detonation wave. The benefits of higher thermal efficiency and reduced compressor size may come at a cost. The first question that arises is the unsteadiness in the flow created by the pulse detonation tubes. A constant pressure combustor has the advantage of supplying a steady and large mass flow rate. The use of the pulse detonation tubes will create an unsteady mass flow which will have currently unknown effects on the turbine located downstream of the combustor. Using multiple pulse detonation tubes will hopefully improve the unsteadiness. The interaction between the turbine and the shock waves exiting the tubes will also have an unknown effect. Noise levels are also a concern with this hybrid system. These unknown effects are being investigated using TURBO, an unsteady turbomachinery flow simulation code developed at Mississippi State University. A baseline case corresponding to a system using a constant pressure combustor with the same mass flow rate achieved with the pulse detonation hybrid system will be investigated first.

Ellis, Matthew T.

2004-01-01

99

Analytical Estimation of Performance Parameters of an Ideal Pulse Detonation Engine  

Microsoft Academic Search

The cycle of an ideal pulse detonation engine (PDE) was theoretically analyzed. A PDE was modeled as a straight tube, one end of which was closed and the other end open. A detonation wave was ignited at the closed end and simultaneously started to propagate toward the open end. When the detonation wave broke out from the open end, a

Takuma Endo; Toshi Fujiwara

2005-01-01

100

Detonation Phenomena of PBX Microsamples  

NASA Astrophysics Data System (ADS)

Detonation study of PBX micro-samples, based on HMX with an inert (HTPB, epoxy) or energetic (GAP) binder was developed on the mesoscale level, using the multifiber optical probes, of 50 ?m resolution, connected directly to a fast electronic streak camera with 0.5 ns of temporal resolution. This record system allows the 2D direct observation of particle-to-particle successive transition of ?-waves through the interparticle binder space. The obtained results show, when the individual coarse HMX particles are subjected to a strong shock wave (30 GPa), the pulsed, double phase, process of energy release (a fast initial phase followed by relatively slow second phase). Also it can be observed the cooperative formation of a multi-head detonation front (DF) in collections of particles surrounded by the binder and the synergetic effect, behind the DF, by the appearing of spatial-temporal dissipative structures, followed by the self-organization of DF oscillations.

Plaksin, Igor; Campos, Jose; Ribeiro, Jose; Mendes, Ricardo

2001-06-01

101

Excitation and quenching of detonation in gases  

NASA Astrophysics Data System (ADS)

The results of investigations on the problems of initiation, propagation, and stabilization of detonation waves and flowing combustible gaseous mixtures are presented. To describe the flows, we used ideal perfect gas equations and two models of the detonation wave: the classical infinitely thin model and a model in which behind the shock wave chemical reactions described by the single-stage kinetics for propane- and methane-air combustible mixtures proceed. Investigations were carried out by both analytical and numerical methods based on the S. K. Godunov scheme on stationary and movable computational meshes with explicit resolution of the bow shock and the surfaces separating gases with different properties.

Levin, V. A.; Manuilovich, I. S.; Markov, V. V.

2010-12-01

102

High temperature detonator  

DOEpatents

A detonator assembly is provided which is usable at high temperatures about 300.degree. C. A detonator body is provided with an internal volume defining an anvil surface. A first acceptor explosive is disposed on the anvil surface. A donor assembly having an ignition element, an explosive material, and a flying plate, are placed in the body effective to accelerate the flying plate to impact the first acceptor explosive on the anvil for detonating the first acceptor explosive. A second acceptor explosive is eccentrically located in detonation relationship with the first acceptor explosive to thereafter effect detonation of a main charge.

Johnson, James O. (Los Alamos, NM); Dinegar, Robert H. (Los Alamos, NM)

1988-01-01

103

Experimental investigation on two-phase pulse detonation engine  

Microsoft Academic Search

This paper presents some results of experimental investigation on a two-phase pulse detonation engine (PDE) model. Proof-of-principle experiments of this model with liquid C8H16\\/air mixture were successfully conducted. Efforts were focused on initiation and propagation of detonation waves by means of one-step detonation initiation method, low-energy ignition system (total stored energy of 50 mJ), and effective Schelkin spiral. Three PDE

Wei Fan; Chuanjun Yan; Xiqiao Huang; Qun Zhang; Longxi Zheng

2003-01-01

104

Optimization of the Thrust Performance of a Pulsed Detonation Engine  

Microsoft Academic Search

The problem of modeling the operation cycle of a pulse detonation engine and estimating its highest possible thrust performance\\u000a is considered. Self-similar and non-self-similar flows in an axisymmetric duct of finite length and variable cross section\\u000a which arise from detonation propagation from the closed end of the duct are studied for the model of an infinitely thin detonation\\u000a wave. Analytical

V. A. Levin; I. S. Manuilovich; V. V. Markov

2010-01-01

105

Interpolation of detonation parameters from experimental particle-velocity records  

Microsoft Academic Search

Measurements from a high resolution particle velocity gauge system are used to investigate reaction zone profiles in several detonating heterogeneous explosives. The analysis of the measured particle motion provides a detailed characterization of the detonation wave front. A major finding is that not all secondary explosives exhibit particle velocity, pressure and volume profiles consistent with the Zeldovich-von Neumann-Doring (ZND) model

B. Hayes; C. M. Tarver

1981-01-01

106

2011 International Workshop on Detonation for Propulsion November 14-15, 2011  

E-print Network

pulse detonation engine (PDE) research at UTA is provided to lay the background for the development of detonation waves to hypersonic flow simulation and power generation. Introduction Pulse Detonation Engine studies of PDEs and RDEs. A summary of these various programs is presented in the following paper. Pulse

Texas at Arlington, University of

107

Detonation Phenomena of PBX Microsamples  

NASA Astrophysics Data System (ADS)

Detonation study of PBX micro-samples, based in HMX with an inert (HTPB, epoxy) or energetic (GAP) binder was performed on the meso-scale level, using the multifiber optical probes of 50 mum of maximum resolution, connected directly to a fast electronic streak camera with 0.6 ns resolution. The direct 2D observation of particle to particle successive transition of transmitted shock wave, through the binder, allows to analyse and to discuss, not only the cooperative formation of a multihead detonation front (DF), in the collection of particles surrounded by binder, but also the synenergetic effect, behind the DF, by the appearing of dissipative structures drawing spatial and temporal DF oscillations.

Plaksin, I.; Campos, J.; Ribeiro, J.; Mendes, R.

2002-07-01

108

Detonation duct gas generator demonstration program  

NASA Technical Reports Server (NTRS)

The feasibility of the generation of detonation waves moving periodically across high speed channel flow is experimentally demonstrated. Such waves are essential to the concept of compressing requirements and increasing the engine pressure compressor with the objective of reducing conventional compressor requirements and increasing the engine thermodynamic efficiency through isochoric energy addition. By generating transient transverse waves, rather than standing waves, shock wave losses are reduced by an order of magnitude. The ultimate objective is to use such detonation ducts downstream of a low pressure gas turbine compressor to produce a high overall pressure ratio thermodynamic cycle. A 4 foot long, 1 inch x 12 inch cross-section, detonation duct was operated in a blow-down mode using compressed air reservoirs. Liquid or vapor propane was injected through injectors or solenoid valves located in the plenum or the duct itself. Detonation waves were generated when the mixture was ignited by a row of spark plugs in the duct wall. Problems with fuel injection and mixing limited the air speeds to about Mach 0.5, frequencies to below 10 Hz, and measured pressure ratios of about 5 to 6. The feasibility of the gas dynamic compression was demonstrated and the critical problem areas were identified.

Wortman, Andrew; Brinlee, Gayl A.; Othmer, Peter; Whelan, Michael A.

1991-01-01

109

Hydrazine vapor detonations  

NASA Technical Reports Server (NTRS)

The detonation velocity and cell widths for hydrazine decomposition were measured over a wide range of temperatures and pressures. The detonation velocity in pure hydrazine was within 5 percent of the calculated C-J velocity. The detonation cell width measurements were interpreted using the Zeldovich-Doering-von Neumann model with a detailed reaction mechanism for hydrazine decomposition. Excellent agreement with experimental data for pure hydrazine was obtained using the empirical relation that detonation cell width was equal to 29 times the kinetically calculated reaction zone length.

Pedley, M. D.; Bishop, C. V.; Benz, F. J.; Bennett, C. A.; Mcclenagan, R. D.

1988-01-01

110

Features of the Detonation of Explosive Aerosuspensions  

NASA Astrophysics Data System (ADS)

The detonation activity of aerosuspensions of particles of a secondary explosive (pentaerythritol tetranitrate) with a mean-volume density of 0.14-1.28 mg/cm3 at the initial pressure of the air in a shock tube of 0.01-0.3 MPa was considered. The dependence of the structure and the main parameters of the detonation wave in an explosive aerosuspension on the concentration of the explosive in it and the initial air pressure as well as the mechanism of propagation of this wave were investigated. The critical (lowest) mean-volume density of an explosive aerosuspension, at which its detonation is still possible, was determined experimentally for different initial air pressures.

Pinaev, A. V.

2014-03-01

111

Bidirectional slapper detonator  

DOEpatents

The disclosure is directed to a bidirectional slapper detonator. One embodiment utilizes a single bridge circuit to detonate a pair of opposing initiating pellets. A line generator embodiment uses a plurality of bridges in electrical series to generate opposing cylindrical wavefronts.

McCormick, Robert N. (Los Alamos, NM); Boyd, Melissa D. (Los Alamos, NM)

1984-01-01

112

Deflagration to detonation transition processes by turbulence-generatingobstacles in pulse detonation engines  

Microsoft Academic Search

The results from a series of detonation experiments conducted to characterize\\u000d\\u000a\\u0009the deflagration-to-detonation transition (DDT) process for ethylene-air\\u000d\\u000a\\u0009mixtures in a 44-mm-square, 1.65-m-long tube are described. Experiments\\u000d\\u000a\\u0009were conducted for both single-shot detonations involving quiescent\\u000d\\u000a\\u0009mixtures as well as multicycle detonations involving dynamic fill.\\u000d\\u000a\\u0009For the experiments, high-frequency pressure and flame emission measurements\\u000d\\u000a\\u0009were made to obtain the compression wave

Seong-Young Lee; J Watts; S Saretto; S Pal; C Conrad; R Woodward; R Santoro

2004-01-01

113

Carbon Detonations in Rapidly Rotating White Dwarfs  

Microsoft Academic Search

We have performed a set of two-dimensional hydrodynamic simulations of the propagation of detonation waves in rapidly rotating white dwarfs. The axisymmetric initial models used in the simulations are in rotational equilibrium and possess a density stratification similar to that of configurations predicted by the merging scenario of Type Ia supernovae. The energy release is approximated by a single exothermic

M. Steinmetz; E. Muller; W. Hillebrandt

1992-01-01

114

Pulse Detonation Engine Test Bed Developed  

NASA Technical Reports Server (NTRS)

A detonation is a supersonic combustion wave. A Pulse Detonation Engine (PDE) repetitively creates a series of detonation waves to take advantage of rapid burning and high peak pressures to efficiently produce thrust. NASA Glenn Research Center's Combustion Branch has developed a PDE test bed that can reproduce the operating conditions that might be encountered in an actual engine. It allows the rapid and cost-efficient evaluation of the technical issues and technologies associated with these engines. The test bed is modular in design. It consists of various length sections of both 2- and 2.6- in. internal-diameter combustor tubes. These tubes can be bolted together to create a variety of combustor configurations. A series of bosses allow instrumentation to be inserted on the tubes. Dynamic pressure sensors and heat flux gauges have been used to characterize the performance of the test bed. The PDE test bed is designed to utilize an existing calorimeter (for heat load measurement) and windowed (for optical access) combustor sections. It uses hydrogen as the fuel, and oxygen and nitrogen are mixed to simulate air. An electronic controller is used to open the hydrogen and air valves (or a continuous flow of air is used) and to fire the spark at the appropriate times. Scheduled tests on the test bed include an evaluation of the pumping ability of the train of detonation waves for use in an ejector and an evaluation of the pollutants formed in a PDE combustor. Glenn's Combustion Branch uses the National Combustor Code (NCC) to perform numerical analyses of PDE's as well as to evaluate alternative detonative combustion devices. Pulse Detonation Engine testbed.

Breisacher, Kevin J.

2002-01-01

115

Detonation propagation in a high loss configuration  

SciTech Connect

This work presents an experimental study of detonation wave propagation in tubes with inner diameters (ID) comparable to the mixture cell size. Propane-oxygen mixtures were used in two test section tubes with inner diameters of 1.27 mm and 6.35 mm. For both test sections, the initial pressure of stoichiometric mixtures was varied to determine the effect on detonation propagation. For the 6.35 mm tube, the equivalence ratio {phi} (where the mixture was {phi} C{sub 3}H{sub 8} + 50{sub 2}) was also varied. Detonations were found to propagate in mixtures with cell sizes as large as five times the diameter of the tube. However, under these conditions, significant losses were observed, resulting in wave propagation velocities as slow as 40% of the CJ velocity U{sub CJ}. A review of relevant literature is presented, followed by experimental details and data. Observed velocity deficits are predicted using models that account for boundary layer growth inside detonation waves.

Jackson, Scott I [Los Alamos National Laboratory; Shepherd, Joseph E [CALTECH

2009-01-01

116

Development of a chemical microthruster based on pulsed detonation  

NASA Astrophysics Data System (ADS)

The development of a microthruster based on gaseous pulsed detonation is presented in this study. The feasibility of cyclic valveless pulsed detonation at frequencies over 100 Hz is first experimentally investigated in a microchannel with 1 mm × 0.6 mm rectangular cross-section. Highly reactive ethylene/oxygen mixtures are utilized to reduce the time and distance required for the reaction wave to run up to detonation in a smooth channel. High-speed visualizations have shown that the reaction waves reach detonative state through highly repeatable flame acceleration and deflagration-to-detonation transition processes in the channel. The validated concepts are implemented for the development of an integrated pulsed detonation microthruster. The microthruster was fabricated using low temperature co-fired ceramic tape technology. The volume of the reaction channel in the microthruster was 58 mm3. Spark electrodes and ion probes were embedded in the ceramic microthruster. The channel and via holes were fabricated using laser cutting techniques. Ion probe measurements showed that the reaction wave propagated at velocities larger than 2000 m s-1 before reaching the channel exit. The pulsed detonation microthruster has been successfully operated at frequencies as high as 200 Hz.

Wu, Ming-Hsun; Lu, Tsung-Hsun

2012-10-01

117

Modeling Hemispheric Detonation Experiments in 2-Dimensions  

SciTech Connect

Experiments have been performed with LX-17 (92.5% TATB and 7.5% Kel-F 800 binder) to study scaling of detonation waves using a dimensional scaling in a hemispherical divergent geometry. We model these experiments using an arbitrary Lagrange-Eulerian (ALE3D) hydrodynamics code, with reactive flow models based on the thermo-chemical code, Cheetah. The thermo-chemical code Cheetah provides a pressure-dependent kinetic rate law, along with an equation of state based on exponential-6 fluid potentials for individual detonation product species, calibrated to high pressures ({approx} few Mbars) and high temperatures (20000K). The parameters for these potentials are fit to a wide variety of experimental data, including shock, compression and sound speed data. For the un-reacted high explosive equation of state we use a modified Murnaghan form. We model the detonator (including the flyer plate) and initiation system in detail. The detonator is composed of LX-16, for which we use a program burn model. Steinberg-Guinan models5 are used for the metal components of the detonator. The booster and high explosive are LX-10 and LX-17, respectively. For both the LX-10 and LX-17, we use a pressure dependent rate law, coupled with a chemical equilibrium equation of state based on Cheetah. For LX-17, the kinetic model includes carbon clustering on the nanometer size scale.

Howard, W M; Fried, L E; Vitello, P A; Druce, R L; Phillips, D; Lee, R; Mudge, S; Roeske, F

2006-06-22

118

Measuring In-Situ Mdf Velocity Of Detonation  

DOEpatents

A system for determining the velocity of detonation of a mild detonation fuse mounted on the surface of a device includes placing the device in a predetermined position with respect to an apparatus that carries a couple of sensors that sense the passage of a detonation wave at first and second spaced locations along the fuse. The sensors operate a timer and the time and distance between the locations is used to determine the velocity of detonation. The sensors are preferably electrical contacts that are held spaced from but close to the fuse such that expansion of the fuse caused by detonation causes the fuse to touch the contact, causing an electrical signal to actuate the timer.

Horine, Frank M. (Albuquerque, NM); James, Jr., Forrest B. (Albuquerque, NM)

2005-10-25

119

Equations of state for explosive detonation products: The PANDA model  

SciTech Connect

This paper discusses a thermochemical model for calculating equations of state (EOS) for the detonation products of explosives. This model, which was first presented at the Eighth Detonation Symposium, is available in the PANDA code and is referred to here as ``the Panda model``. The basic features of the PANDA model are as follows. (1) Statistical-mechanical theories are used to construct EOS tables for each of the chemical species that are to be allowed in the detonation products. (2) The ideal mixing model is used to compute the thermodynamic functions for a mixture of these species, and the composition of the system is determined from assumption of chemical equilibrium. (3) For hydrocode calculations, the detonation product EOS are used in tabular form, together with a reactive burn model that allows description of shock-induced initiation and growth or failure as well as ideal detonation wave propagation. This model has been implemented in the three-dimensional Eulerian code, CTH.

Kerley, G.I.

1994-05-01

120

Detonation Meso-Scale Tests for Energetic Materials  

NASA Astrophysics Data System (ADS)

The objective of the present study is to characterize, on the meso-scale level, the detonation behaviour of PBX based on HMX , based in the minimisation of the test samples of energetic materials up to 10 mg. The development of a non-intrusive, high resolution, optical metrology procedures, using multi-fibber strip, allows the testing of PBX micro-samples, formed by few crystals surrounded by binder, with the simultaneous registration of parameters as local detonation velocity and pressure, geometrical shape of detonation front and the structure of the shock-to-detonation transition zone. The enhanced information allows a better understanding of the processes of formation and propagation of detonation wave. This procedure can be applied to the study of new advanced energetic materials.

Plaksin, I.; Campos, J.; Ribeiro, J.; Mendes, R.; Gois, J.; Portugal, A.; Simoes, P.; Pedroso, L.

2002-07-01

121

Influence of the preheating of a working medium on the thermodynamic efficiency of pulse-detonation-engine propulsion modules  

Microsoft Academic Search

A theoretical substantiation of calculation of the thermodynamic cycle of engines with detonation fuel combustion, which is realized in propulsion modules of pulse detonation engines, has been given. A system of equations for calculation of the parameters of detonation combustion waves under different conditions of their excitation has been obtained. On their basis, investigations of the influence of different factors

Yu. N. Nechaev

2010-01-01

122

Detonation Diffraction into a Confined Volume  

E-print Network

Detonation diffraction has been, and remains, an active area of research. However, detonation diffraction into a confined volume, and specifically the transformation of a planar detonation into a cylindrical detonation, is an area which has received...

Polley, Nolan Lee

2012-02-14

123

Molecular Dynamics Simulations of Weak Detonations Morag Am-Shallem,1  

E-print Network

of a stable fast reactive shock wave. The terminal shock velocity is independent of the initiation conditions behind the shock front. The dependence of the shock velocity on crystal nonlinear compressibility of the detonation wave on microscopic potential parameters was investigated. An increase in detonation velocity

Kosloff, Ronnie

124

High efficiency detonation internal combustion engine (DICE)  

NASA Astrophysics Data System (ADS)

Controlled detonation combustion could be used in future internal combustion engines to achieve high cycle efficiency and minimize NO(x) formation, if conventional design limitations are removed. An engine is proposed that uses a separate detonation combustion chamber which discharges tangentially into an expansion chamber formed by the piston and cylinder at top dead center. The expansion chamber is designed to efficiently store a portion of the detonation wave's kinetic energy in the form of a vortex, which is subsequently converted into static pressure. The rapid burning, followed by 'leaning' through mixing with air in the vortex chamber, may reduce the formation of NO(x) and unburned hydrocarbons as compared to conventional combustion. The thermodynamic aspects of detonation combustion compared to either constant volume or constant pressure combustion yield a significant increase in combustion compression ratio for fuels such as natural gas. The shock wave propagation through the vortex chamber is described with a shock-capturing finite element Euler flow code supporting the premise of vortex storage and rapid-mixing characteristics.

Loth, Eric; Loth, John; Loth, Frank

1992-07-01

125

Modeling of Explosion Gas Dynamics with Account of Detonation  

NASA Astrophysics Data System (ADS)

The physical and hydrodynamic processes in the initial phase of explosion of condensed explosives in the air have been considered. The role of the processes of energy release connected with the explosive detonation has been analyzed. The equations of formal kinetics for modeling the processes of transformation of the original substance into detonation products have been described. The results obtained with the use of the equation of state of an ideal gas with a constant adiabatic index have been compared with calculations, where for the equation of state wide-range tables of properties of the air and explosion products were used. The stage of detonation of an explosive is included in the self-consistent hydrodynamic model used for describing the explosion processes from the moment of initiation of the detonation wave to the moment the air shock wave is formed, as well as in describing its propagation and attenuation.

Morozov, D. O.

2013-11-01

126

Approximation Particulaire D'une Onde de Detonation  

NASA Astrophysics Data System (ADS)

In the study of Detonation waves a difficulty arises often, the choice of an equation of state for mixtures of undecomposed explosive and detonation products. The particle method presented in this paper is an attempt to avoid that kind of difficulty. This is done by using a particle scheme without mesh, introduced by Gingold and Monaghan, to solve the equation of motion and a probability law to approximate the reaction rate. The first numerical results are given.

Bourgeade, A.

127

Detonation Shock Radius Experiments.  

NASA Astrophysics Data System (ADS)

A previous passover experiment [1] was designed to create a complex detonation transient used in validating a reduced, asymptotically derived description of detonation shock dynamics (DSD). An underlying question remained on determining the location of the initial detonation shock radius to start the DSD simulation with respect to the dynamical response of the initiation system coupling's to the main charge. This paper concentrates on determining the initial shock radius required of such DSD governed problems. `Cut-back' experiments of PBX-9501 were conducted using an initiation system that sought to optimize the transferred detonation to the desired constant radius, hemispherical shape. Streak camera techniques captured the breakout on three of the prism's surfaces for time-of-arrival data. The paper includes comparisons to simulations using constant volume explosion and high pressure hot spots. The results of the experiments and simulation efforts provide fundamental design considerations for actual explosive systems and verify necessary conditions from which the asymptotic theory of DSD may apply. [1] Lambert, D., Stewart, D. Scott and Yoo, S. and Wescott, B., ``Experimental Validation of Detonation Shock Dynamics in Condensed Explosives. J. of Fluid Mechs., Vol. 546, pp.227-253 (2006).

Lambert, David; Debes, Joshua; Stewart, Scott; Yoo, Sunhee

2007-06-01

128

Discrete approximations of detonation flows with structured detonation reaction zones by discontinuous front models: A program burn algorithm based on detonation shock dynamics  

SciTech Connect

In the design of explosive systems the generic problem that one must consider is the propagation of a well-developed detonation wave sweeping through an explosive charge with a complex shape. At a given instant of time the lead detonation shock is a surface that occupies a region of the explosive and has a dimension that is characteristic of the explosive device, typically on the scale of meters. The detonation shock is powered by a detonation reaction zone, sitting immediately behind the shock, which is on the scale of 1 millimeter or less. Thus, the ratio of the reaction zone thickness to the device dimension is of the order of 1/1,000 or less. This scale disparity can lead to great difficulties in computing three-dimensional detonation dynamics. An attack on the dilemma for the computation of detonation systems has lead to the invention of sub-scale models for a propagating detonation front that they refer to herein as program burn models. The program burn model seeks not to resolve the fine scale of the reaction zone in the sense of a DNS simulation. The goal of a program burn simulation is to resolve the hydrodynamics in the inert product gases on a grid much coarser than that required to resolve a physical reaction zone. The authors first show that traditional program burn algorithms for detonation hydrocodes used for explosive design are inconsistent and yield incorrect shock dynamic behavior. To overcome these inconsistencies, they are developing a new class of program burn models based on detonation shock dynamic (DSD) theory. It is hoped that this new class will yield a consistent and robust algorithm which reflects the correct shock dynamic behavior.

Bdzil, J.B. [Los Alamos National Lab., NM (United States); Jackson, T.L. [Univ. of Illinois, Urbana, IL (United States). Center for Simulation of Advanced Rockets; Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States). Theoretical and Applied Mechanics

1999-02-02

129

Reverse slapper detonator  

DOEpatents

A reverse slapper detonator (70), and methodology related thereto, are provided. The detonator (70) is adapted to be driven by a pulse of electric power from an external source (80). A conductor (20) is disposed along the top (14), side (18), and bottom (16) surfaces of a sheetlike insulator (12). Part of the conductor (20) comprises a bridge (28), and an aperture (30) is positioned within the conductor (20), with the bridge (28) and the aperture (30) located on opposite sides of the insulator (12). A barrel (40) and related explosive charge (50) are positioned adjacent to and in alignment with the aperture (30), and the bridge (28) is buttressed with a backing layer (60). When the electric power pulse vaporizes the bridge (28), a portion of the insulator (12) is propelled through the aperture (30) and barrel (40), and against the explosive charge (50), thereby detonating it.

Weingart, Richard C. (Livermore, CA)

1990-01-01

130

Synchro-ballistic recording of detonation phenomena  

SciTech Connect

Synchro-ballistic use of rotating-mirror streak cameras allows for detailed recording of high-speed events of known velocity and direction. After an introduction to the synchro-ballistic technique, this paper details two diverse applications of the technique as applied in the field of high-explosives research. In the first series of experiments detonation-front shape is recorded as the arriving detonation shock wave tilts an obliquely mounted mirror, causing reflected light to be deflected from the imaging lens. These tests were conducted for the purpose of calibrating and confirming the asymptotic Detonation Shock Dynamics (DSD) theory of Bdzil and Stewart. The phase velocities of the events range from ten to thirty millimeters per microsecond. Optical magnification is set for optimal use of the film`s spatial dimension and the phase velocity is adjusted to provide synchronization at the camera`s maximum writing speed. Initial calibration of the technique is undertaken using a cylindrical HE geometry over a range of charge diameters and of sufficient length-to-diameter ratio to insure a stable detonation wave. The final experiment utilizes an arc-shaped explosive charge, resulting in an asymmetric detonation-front record. The second series of experiments consists of photographing a shaped-charge jet having a velocity range of two to nine millimeters per microsecond. To accommodate the range of velocities it is necessary to fire several tests, each synchronized to a different section of the jet. The experimental apparatus consists of a vacuum chamber to preclude atmospheric ablation of the jet tip with shocked-argon back lighting to produce a shadow-graph image.

Critchfield, R.R.; Asay, B.W.; Bdzil, J.B.; Davis, W.C.; Ferm, E.N.; Idar, D.J.

1997-09-01

131

In-Situ Continuous Detonation Velocity Measurements Using Fiber-optic Bragg Grating Sensors  

SciTech Connect

In order to fully calibrate hydrocodes and dynamic chemistry burn models, initiation and detonation research requires continuous measurement of low order detonation velocities as the detonation runs up to full order detonation for a given density and initiation pressure pulse. A novel detector of detonation velocity is presented using a 125 micron diameter optical fiber with an integral chirped fiber Bragg grating as an intrinsic sensor. This fiber is embedded in the explosive under study and interrogated during detonation as the fiber Bragg grating scatters light back along the fiber to a photodiode, producing a return signal dependant on the convolution integral of the grating reflection bandpass, the ASE intensity profile and the photodetector response curve. Detonation velocity is measured as the decrease in reflected light exiting the fiber as the grating is consumed when the detonation reaction zone proceeds along the fiber sensor axis. This small fiber probe causes minimal perturbation to the detonation wave and can measure detonation velocities along path lengths tens of millimeters long. Experimental details of the associated equipment and preliminary data in the form of continuous detonation velocity records within nitromethane and PBX-9502 are presented.

Benterou, J; Udd, E; Wilkins, P; Roeske, F; Roos, E; Jackson, D

2007-07-25

132

Characterizing Detonator Output Using Dynamic Witness Plates  

NASA Astrophysics Data System (ADS)

A sub-microsecond, time-resolved micro-particle-image velocimetry (PIV) system is developed to investigate the output of explosive detonators. Detonator output is directed into a transparent solid that serves as a dynamic witness plate and instantaneous shock and material velocities are measured in a two-dimensional plane cutting through the shock wave as it propagates through the solid. For the case of unloaded initiators (e.g. exploding bridge wires, exploding foil initiators, etc.) the witness plate serves as a surrogate for the explosive material that would normally be detonated. The velocity-field measurements quantify the velocity of the shocked material and visualize the geometry of the shocked region. Furthermore, the time-evolution of the velocity-field can be measured at intervals as small as 10 ns using the PIV system. Current experimental results of unloaded exploding bridge wire output in polydimethylsiloxane (PDMS) witness plates demonstrate 20 MHz velocity-field sampling just 300 ns after initiation of the wire. Successful application of the PIV system to full-up explosive detonator output is also demonstrated.

Murphy, Michael; Adrian, Ronald

2009-06-01

133

Nonequilibrium detonation of composite explosives  

SciTech Connect

The effect of nonequilibrium diffusional flow on detonation velocities in composite explosives is examined. Detonation conditions are derived for complete equilibrium, temperature and pressure equilibrium, and two forms of pressure equilibrium. Partial equilibria are associated with systems which have not had sufficient time for transport to smooth out the gradients between spatially separate regions. The nonequilibrium detonation conditions are implemented in the CHEQ equation of state code. We show that the detonation velocity decreases as the non-chemical degrees of freedom of the explosive are allowed to equilibrate. It is only when the chemical degrees of freedom are allowed to equilibrate that the detonation velocity increases.

Nichols III, A.L.

1997-07-01

134

Development of a Detonation Profile Test for Studying Aging Effects in LX17  

Microsoft Academic Search

A new small-scale Detonation Profile Test (DPT) is being developed to investigate aging effects on the detonation behavior of insensitive high explosives. The experiment involves initiating a small LX-17 cylindrical charge (12.7-19.1 mm diameter x 25.4-33 mm long) and measuring the velocity and curvature of the emerging detonation wave using a streak camera. Results for 12.7 mm diameter unconfined LX-17

T Tran; P Lewis; C Tarver; J Maienschein; R Druce; R Lee; F Roeske

2002-01-01

135

An engineering method for calculating the parameters and characteristics of pulse detonation engines  

Microsoft Academic Search

Theoretical fundamentals for calculating the thermodynamic cycle of engines with fuel detonation (FD cycle), which is realized\\u000a in the thrust units of pulse detonation engines (PDE), are presented. A system of equations for calculating the parameters\\u000a of the detonation waves under various conditions of their initiation is derived. These equations were used to examine how\\u000a various factors influence the parameters

Yu. N. Nechaev

2009-01-01

136

Theory of cellular detonations in gases. Part 1. Stability limits at strong overdrive  

NASA Astrophysics Data System (ADS)

A stability analysis of detonation waves is carried out at strong overdrive and in the Newtonian limit (small difference between the specific heats at constant pressure and at constant volume). The instability threshold is determined. An analytical expression of the dispersion relation and a linear integral-differential equation for the evolution of the detonation front, both valid at onset of the instability, are obtained. The analysis is valid for an arbitrary chemistry compatible with stable or weakly unstable gaseous detonations.

Clavin, Paul; He, Longting

137

Theory of cellular detonations in gases. Part 2. Mach-stem formation at strong overdrive  

NASA Astrophysics Data System (ADS)

A weakly nonlinear analysis of cellular detonations at onset of the instability against transverse disturbances is carried out in the Newtonian limit at strong overdrive. A nonlinear integral-differential equation describing the formation of cusps representative of Mach-stems on the detonation front is obtained as an asymptotic solution of the reactive Euler equations. A numerical study of this equation exhibits patterns that are similar to the cellular structures observed experimentally in gaseous detonation waves.

Clavin, Paul; Denet, Bruno

138

Printable sensors for explosive detonation  

NASA Astrophysics Data System (ADS)

Here, we report the development of an organic thin film transistor (OTFT) based on printable solution processed polymers and employing a quantum tunnelling composite material as a sensor to convert the pressure wave output from detonation transmission tubing (shock tube) into an inherently amplified electronic signal for explosives initiation. The organic electronic detector allows detection of the signal in a low voltage operating range, an essential feature for sites employing live ordinances that is not provided by conventional electronic devices. We show that a 30-fold change in detector response is possible using the presented detector assembly. Degradation of the OTFT response with both time and repeated voltage scans was characterised, and device lifetime is shown to be consistent with the requirements for on-site printing and usage. The integration of a low cost organic electronic detector with inexpensive shock tube transmission fuse presents attractive avenues for the development of cheap and simple assemblies for precisely timed initiation of explosive chains.

Griffith, Matthew J.; Cooling, Nathan A.; Elkington, Daniel C.; Muller, Elmar; Belcher, Warwick J.; Dastoor, Paul C.

2014-10-01

139

Non ideal detonation of emulsion explosives mixed with metal particles  

NASA Astrophysics Data System (ADS)

The detonation of ammonium nitrate based compositions like emulsion explosives (EX) mixed with metal particles has been investigated experimentally. Aluminium powder with a mean particle size of 10 ?m was used, and the mass concentration of aluminum on the explosive charge was ranged from 0 to 30%. The values of the detonation velocity, the pressure attenuation -- P(x) -- of detonation front amplitude in a standard PMMA monitor and manganin gauges pressure-time histories are shown as a function of the explosive charge porosity and specific mass. All these parameters except the pressure-times histories have been evaluated using the multi fiber optical probe (MFOP) method which is based on the use of an optical fiber strip, with 64 independent optical fibers. The MFOP allow a quasi continuous evaluation of the detonation wave run propagation and the assessment to spatial resolved measurements of the shock wave induced in the PMMA barrier which in turns allows a detailed characterization of the detonation reaction zone structure. Results of that characterization process are presented and discussed for aluminized and non aluminized EX. Moreover, the effect of the mass concentration of the sensitizing agent (hollow glass micro-balloons) on the non monotonic detonation velocity variation, for EX, will be discussed.

Mendes, R.; Ribeiro, J.; Plaksin, I.; Campos, J.

2011-06-01

140

Minimum tube diameters for steady propagation of gaseous detonations  

NASA Astrophysics Data System (ADS)

Recent experimental results on detonation limits are reported in this paper. A parametric study was carried out to determine the minimum tube diameters for steady detonation propagation in five different hydrocarbon fuel-oxygen combustible mixtures and in five polycarbonate test tube diameters ranging from 50.8 mm down to a small scale of 1.5 mm. The wave propagation in the tube was monitored by optical fibers. By decreasing the initial pressure, hence the sensitivity of the mixture, the onset of limits is indicated by an abrupt drop in the steady detonation velocity after a short distance of travel. From the measured wave velocities inside the test tube, the critical pressure corresponding to the limit and the minimum tube diameters for the propagation of the detonation can be obtained. The present experimental results are in good agreement with previous studies and show that the measured minimum tube diameters can be reasonably estimated on the basis of the /3 rule over a wide range of conditions, where is the detonation cell size. These new data shall be useful for safety assessment in process industries and in developing and validating models for detonation limits.

Gao, Y.; Ng, H. D.; Lee, J. H. S.

2014-07-01

141

New detonation concepts for propulsion and power generation  

NASA Astrophysics Data System (ADS)

A series of related analytical and experimental studies are focused on utilizing detonations for emerging propulsion and power generation devices. An understanding of the physical and thermodynamic processes for this unsteady thermodynamic cycle has taken over 100 years to develop. An overview of the thermodynamic processes and development history is provided. Thermodynamic cycle analysis of detonation-based systems has often been studied using surrogate models. A real gas model is used for a thermal efficiency prediction of a detonation wave based on the work and heat specified by process path diagrams and a control volume analysis. A combined first and second law analysis aids in understanding performance trends for different initial conditions. A cycle analysis model for an airbreathing, rotating detonation wave engine (RDE) is presented. The engine consists of a steady inlet system with an isolator which delivers air into an annular combustor. A detonation wave continuously rotates around the combustor with side relief as the flow expands towards the nozzle. Air and fuel enter the combustor when the rarefaction wave pressure behind the detonation front drops to the inlet supply pressure. To create a stable RDE, the inlet pressure is matched in a convergence process with the average combustor pressure by increasing the annulus channel width with respect to the isolator channel. Performance of this engine is considered using several parametric studies. RDEs require a fuel injection system that can cycle beyond the limits of mechanical valves. Fuel injectors composed of an orifice connected to a small plenum cavity were mounted on a detonation tube. These fuel injectors, termed fluidic valves, utilize their geometry and a supply pressure to deliver fuel and contain no moving parts. Their behavior is characterized in order to determine their feasibility for integration with high-frequency RDEs. Parametric studies have been conducted with the type of fuel injected, the orifice diameter, and the plenum cavity pressure. Results indicate that the detonation wave pressure temporarily interrupts the fluidic valve supply, but the wave products can be quickly expelled by the fresh fuel supply to allow for refueling. The interruption time of the valve scales with injection and detonation wave pressure ratios as well as a characteristic time. The feasibility of using a detonation wave as a source for producing power in conjunction with a linear generator is considered. Such a facility can be constructed by placing a piston--spring system at the end of a pulsed detonation engine (PDE). Once the detonation wave reflects off the piston, oscillations of the system drive the linear generator. An experimental facility was developed to explore the interaction of a gaseous detonation wave with the piston. Experimental results were then used to develop a model for the interaction. Governing equations for two engine designs are developed and trends are established to indicate a feasible design space for future development.

Braun, Eric M.

142

Miniature plasma accelerating detonator and method of detonating insensitive materials  

DOEpatents

The invention is a detonator for use with high explosives. The detonator comprises a pair of parallel rail electrodes connected to a power supply. By shorting the electrodes at one end, a plasma is generated and accelerated toward the other end to impact against explosives. A projectile can be arranged between the rails to be accelerated by the plasma. An alternative arrangement is to a coaxial electrode construction. The invention also relates to a method of detonating explosives. 3 figs.

Bickes, R.W. Jr.; Kopczewski, M.R.; Schwarz, A.C.

1985-01-04

143

Miniature plasma accelerating detonator and method of detonating insensitive materials  

DOEpatents

The invention is a detonator for use with high explosives. The detonator comprises a pair of parallel rail electrodes connected to a power supply. By shorting the electrodes at one end, a plasma is generated and accelerated toward the other end to impact against explosives. A projectile can be arranged between the rails to be accelerated by the plasma. An alternative arrangement is to a coaxial electrode construction. The invention also relates to a method of detonating explosives.

Bickes, Jr., Robert W. (Albuquerque, NM); Kopczewski, Michael R. (Albuquerque, NM); Schwarz, Alfred C. (Albuquerque, NM)

1986-01-01

144

Material properties effects on the detonation spreading and propagation of diaminoazoxyfurazan (DAAF)  

SciTech Connect

Recent dynamic testing of Diaminoazoxyfurazan (DAAF) has focused on understanding the material properties affecting the detonation propagation, spreading, behavior and symmetry. Small scale gap testing and wedge testing focus on the sensitivity to shock with the gap test including the effects of particle size and density. Floret testing investigates the detonation spreading as it is affected by particle size, density, and binder content. The polyrho testing illustrates the effects of density and binder content on the detonation velocity. Finally the detonation spreading effect can be most dramatically seen in the Mushroom and Onionskin tests where the variations due to density gradients, pressing methods and geometry can be seen on the wave breakout behavior.

Francois, Elizabeth Green [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory; Novak, Alan M [Los Alamos National Laboratory; Kennedy, James E [HERE LLC

2010-01-01

145

The mach reflection of a detonation based on soot track measurements  

Microsoft Academic Search

This paper presents a series of soot tracks formed by gaseous detonation waves diffracting around wedges with different wedge angles. These cellular structure patterns describe the Mach-reflection processes of a detonation and reveal some unique characteristics. They can be used to analyze the relationship between the trajectory angle of the triple point, wedge angle, and initial pressure in Mach reflection.

Guo Changming; Zhang Deliang; Xie Wei

2001-01-01

146

The Mach Reflection of a Detonation Based on Soot Track Measurements  

Microsoft Academic Search

This paper presents a series of soot tracks formed by gaseous detonation waves diffracting around wedges with different wedge angles. These cellular structure patterns describe the Mach-reflection processes of a detonation and reveal some unique characteristics. They can be used to analyze the relationship between the trajectory angle of the triple point, wedge angle, and initial pressure in Mach reflection.

CHANGMING GUO; DELIANG ZHANG; WEI XIE

147

Laser supported solid state absorption fronts in silica  

SciTech Connect

We develop a model based on simulation and experiment that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm{sup 2}) laser exposure. We find that the absorption front velocity is constant in time and is nearly linear in laser intensity. Further, this model can explain the dependence of laser damage site size on these parameters. This behavior is driven principally by the temperature-activated deep sub band-gap optical absorptivity, free electron transport and thermal diffusion in defect-free silica for temperatures up to 15,000K and pressures < 15GPa. The regime of parameter space critical to this problem spans and extends that measured by other means. It serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

Carr, C W; Bude, J D

2010-02-09

148

Chemical Equilibrium Detonation  

NASA Astrophysics Data System (ADS)

Energetic materials are unique for having a strong exothermic reactivity, which has made them desirable for both military and commercial applications. The fundamental principles outlined in this chapter pertain to the study of detonation in both gas-phase and condensed-phase energetic materials, but our main focus will be on the condensed ones, particularly on high explosives (HEs). They share many properties with other classes of condensed energetic compounds such as propellants and pyrotechnics, but a detailed understanding of detonation is especially important for numerous HE applications. The usage and study of HE materials goes back more than a century, but many questions remain to be answered, e.g., on their reaction pathways at high pressures and temperatures, chemical properties, etc.

Bastea, Sorin; Fried, Laurence E.

149

Detonation Shock Dynamics for Porous Explosives and Energetic Materials  

NASA Astrophysics Data System (ADS)

An explosive powder subjected to mechanical or thermal loading undergoes micro structural changes that cause the density to increase and the material to be compacted. The energy that drives compaction is absorbed by the material as the microstructure changes and the specific internal energy of the solid-void mixture increases due to the increase in density as voids become occupied by solids. These changes affect the reactive properties of the material and the mechanics and dynamics of detonation waves in explosive powders. The effects of explosive powder compaction on detonation wave dynamics have not been well characterized. Here we use the theory of Detonation Shock Dynamics (DSD) to analyze the effects of compaction on the dynamics and geometry of detonation waves in explosive powders. We apply DSD theory using a simplified equation of state (EOS) that has been shown to represent the effects of compaction that lead to deflagration to detonation transition in explosive powders. We will show results from the numerical solution of the DSD theory equations as well as from asymptotic DSD theory.

Saenz, Juan A.; Stewart, D. Scott

2009-12-01

150

HEAT TRANSFER ANALYSIS OF A PULSE DETONATION  

E-print Network

HEAT TRANSFER ANALYSIS OF A PULSE DETONATION ENGINE by NEELIMA KALIDINDI Presented to the Faculty support. November 23, 2009 #12;iv ABSTRACT HEAT TRANSFER ANALYSIS OF A PULSE DETONATION ENGINE NEELIMA ........................................................................................... 1 1.1 Pulse Detonation Engine ................................................................. 1 1

Texas at Arlington, University of

151

Helium Detonations on Neutron Stars  

Microsoft Academic Search

We present the results of a numerical study of helium detonations on the surfaces of neutron stars. We describe two-dimensional simulations of the evolution of a detonation as it breaks through the accreted envelope of the neutron star and propagates laterally through the accreted material. The detonation front propagates laterally at nearly the Chapman-Jouguet velocity, v=1.3×109 cm s-1. A series

M. Zingale; F. X. Timmes; B. Fryxell; D. Q. Lamb; K. Olson; A. C. Calder; L. J. Dursi; P. Ricker; R. Rosner; P. MacNeice; H. M. Tufo

2001-01-01

152

The Effect of the Pre-detonation Stellar Internal Velocity Profile on the Nucleosynthetic Yields in Type Ia Supernova  

NASA Astrophysics Data System (ADS)

A common model of the explosion mechanism of Type Ia supernovae is based on a delayed detonation of a white dwarf. A variety of models differ primarily in the method by which the deflagration leads to a detonation. A common feature of the models, however, is that all of them involve the propagation of the detonation through a white dwarf that is either expanding or contracting, where the stellar internal velocity profile depends on both time and space. In this work, we investigate the effects of the pre-detonation stellar internal velocity profile and the post-detonation velocity of expansion on the production of ?-particle nuclei, including 56Ni, which are the primary nuclei produced by the detonation wave. We perform one-dimensional hydrodynamic simulations of the explosion phase of the white dwarf for center and off-center detonations with five different stellar velocity profiles at the onset of the detonation. In order to follow the complex flows and to calculate the nucleosynthetic yields, approximately 10,000 tracer particles were added to every simulation. We observe two distinct post-detonation expansion phases: rarefaction and bulk expansion. Almost all the burning to 56Ni occurs only in the rarefaction phase, and its expansion timescale is influenced by pre-existing flow structure in the star, in particular by the pre-detonation stellar velocity profile. We find that the mass fractions of the ?-particle nuclei, including 56Ni, are tight functions of the empirical physical parameter ?up/v down, where ?up is the mass density immediately upstream of the detonation wave front and v down is the velocity of the flow immediately downstream of the detonation wave front. We also find that v down depends on the pre-detonation flow velocity. We conclude that the properties of the pre-existing flow, in particular the internal stellar velocity profile, influence the final isotopic composition of burned matter produced by the detonation.

Kim, Yeunjin; Jordan, G. C., IV; Graziani, Carlo; Meyer, B. S.; Lamb, D. Q.; Truran, J. W.

2013-07-01

153

Low voltage nonprimary explosive detonator  

DOEpatents

A low voltage, electrically actuated, nonprimary explosive detonator is disclosed wherein said detonation is achieved by means of an explosive train in which a deflagration-to-detonation transition is made to occur. The explosive train is confined within a cylindrical body and positioned adjacent to low voltage ignition means have electrical leads extending outwardly from the cylindrical confining body. Application of a low voltage current to the electrical leads ignites a self-sustained deflagration in a donor portion of the explosive train which then is made to undergo a transition to detonation further down the train.

Dinegar, Robert H. (Los Alamos, NM); Kirkham, John (Newbury, GB2)

1982-01-01

154

Initiation of detonation regimes in hybrid two-phase mixtures  

NASA Astrophysics Data System (ADS)

The problem of detonation initiation is studied in the case of hybrid two-phase mixtures consisting of a hydrogen-air gaseous mixture with suspended fine aluminium particles. In preceding works on this subject, investigation of the steady propagation regimes has shown that three main propagation regimes could exist: the Pseudo-Gas Detonation (PGD), the Single-Front Detonation (SFD), and the Double-Front Detonation (DFD). In the present study, a one-dimensional unsteady numerical code has been improved to study the build-up of the detonation in a heterogeneous solid particle gas mixture contained in a tube. The initiation is simulated by the deposition of a given energy in a point source explosion, and the formation of the detonation is observed over distances of 15 m to 30 m. As the code has been designed to run on a micro-computer, memory limitations preclude sufficient accuracy for quantitative results, however, good qualitative agreement has been found with the results of the steady analysis. In addition, it has been demonstrated that when both PGD and SFD could exist at the same particle concentration, the PGD regime was unstable and was able to exist only over a limited distance (a few meters): after some time, the reaction of aluminium particles in the unsteady flow perturbs the leading wave and accelerates it to the SFD regime. Influence of particle diameter and of initiation energy are examined.

Khasainov, B. A.; Veyssiere, B.

1996-06-01

155

Mechanisms of detonation formation due to a temperature gradient  

NASA Astrophysics Data System (ADS)

Emergence of a detonation in a homogeneous, exothermically reacting medium can be deemed to occur in two phases. The first phase processes the medium so as to create conditions ripe for the onset of detonation. The actual events leading up to preconditioning may vary from one experiment to the next, but typically, at the end of this stage the medium is hot and in a state of nonuniformity. The second phase consists of the actual formation of the detonation wave via chemico-gasdynamic interactions. This paper considers an idealized medium with simple, rate-sensitive kinetics for which the preconditioned state is modelled as one with an initially prescribed linear gradient of temperature. Accurate and well-resolved numerical computations are carrried out to determine the mode of detonation formation as a function of the size of the initial gradient. For shallow gradients, the result is a decelerating supersonic reaction wave, a weak detonation, whose trajectory is dictated by the initial temperature profile, with only weak intervention from hydrodynamics. If the domain is long enough, or the gradient less shallow, the wave slows down to the Chapman-Jouguet speed and undergoes a swift transition to the ZND structure. For sharp gradients, gasdynamic nonlinearity plays a much stronger role. Now the path to detonation is through an accelerating pulse that runs ahead of the reaction wave and rearranges the induction-time distribution there to one that bears little resemblance to that corresponding to the initial temperature gradient. The pulse amplifies and steepens, transforming itself into a complex consisting of a lead shock, an induction zone, and a following fast deflagration. As the pulse advances, its three constituent entities attain progressively higher levels of mutual coherence, to emerge as a ZND detonation. For initial gradients that are intermediate in size, aspects of both the extreme scenarios appear in the path to detonation. The novel aspect of this study resides in the fact that it is guided by, and its results are compared with, existing asymptotic analyses of detonation evolution.

Kapila, A. K.; Schwendeman, D. W.; Quirk, J. J.; Hawa, T.

2002-12-01

156

Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power  

NASA Technical Reports Server (NTRS)

The prospects for realizing an integrated pulse detonation propulsion and magnetohydrodynamic (MHD) power system are examined. First, energy requirements for direct detonation initiation of various fuel-oxygen and fuel-air mixtures are deduced from available experimental data and theoretical models. Second, the pumping power requirements for effective chamber scavenging are examined through the introduction of a scavenging ratio parameter and a scavenging efficiency parameter. A series of laboratory experiments were carried out to investigate the basic engineering performance characteristics of a pulse detonation-driven MHD electric power generator. In these experiments, stoichiometric oxy-acetylene mixtures seeded with a cesium hydroxide/methanol spray were detonated at atmospheric pressure in a 1-m-long tube having an i.d. of 2.54 cm. Experiments with a plasma diagnostic channel attached to the end of the tube confirmed the attainment of detonation conditions (p(sub 2)/p(sub 1) approx. 34 and D approx. 2,400 m/sec) and enabled the direct measurement of current density and electrical conductivity (=6 S/m) behind the detonation wave front. In a second set of experiments, a 30-cm-long continuous electrode Faraday channel, having a height of 2.54 cm and a width of 2 cm, was attached to the end of the tube using an area transition duct. The Faraday channel was inserted in applied magnetic fields of 0.6 and 0.95 T. and the electrodes were connected to an active loading circuit to characterize power extraction dependence on load impedance while also simulating higher effective magnetic induction. The experiments indicated peak power extraction at a load impedance between 5 and 10 Ohm. The measured power density was in reasonable agreement with a simple electrodynamic model incorporating a correction for near-electrode potential losses. The time-resolved thrust characteristics of the system were also measured, and it was found that the MHD interaction exerted a negligible influence on system thrust and that the measured I(sub sp) of the system (200 sec) exceeded that computed for an equivalent nozzleless rocket (120 sec).

Litchford, R. J.; Lyles, Garry M. (Technical Monitor)

2001-01-01

157

Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power  

NASA Technical Reports Server (NTRS)

The prospects for realizing an integrated pulse detonation propulsion and magnetohydrodynamic (MHD) power system are examined. First, energy requirements for direct detonation initiation of various fuel-oxygen and fuel-air mixtures are deduced from available experimental data and theoretical models. Second, the pumping power requirements for effective chamber scavenging are examined through the introduction of a scavenging ratio parameter and a scavenging efficiency parameter. A series of laboratory experiments were carried out to investigate the basic engineering performance characteristics of a pulse detonation-driven MHD electric power generator. In these experiments, stoichiometric oxy-acetylene mixtures seeded with a cesium hydroxide/methanol spray were detonated at atmospheric pressure in a 1-m-long tube having an i.d. of 2.54 cm. Experiments with a plasma diagnostic channel attached to the end of the tube confirmed the attainment of detonation conditions (p2/p1 approximately 34 and D approximately 2,400 m/sec) and enabled the direct measurement of current density and electrical conductivity (approximately = 6 S/m) behind the detonation wave front, In a second set of experiments, a 30-cm-long continuous electrode Faraday channel, having a height of 2.54 cm and a width of 2 cm, was attached to the end of the tube using an area transition duct. The Faraday channel was inserted in applied magnetic fields of 0.6 and 0.95 T, and the electrodes were connected to an active loading circuit to characterize power extraction dependence on load impedance while also simulating higher effective magnetic induction. The experiments indicated peak power extraction at a load impedance between 5 and 10 Omega. The measured power density was in reasonable agreement with a simple electrodynamic model incorporating a correction for near-electrode potential losses. The time-resolved thrust characteristics of the system were also measured, and it was found that the NM interaction exerted a negligible influence on system thrust and that the measured I(sub sp) of the system (200 see) exceeded that computed for an equivalent nozzleless rocket (120 see).

Litchford, Ron J.

2001-01-01

158

Smooth blasting with the electronic delay detonator  

SciTech Connect

The authors utilized electronic detonators (EDs) to investigate the effect of high detonator delay accuracy on overbreak, remaining rock damage, and surface smoothness, in comparison with that of long-period delay detonators (0.25 sec interval) PDs. The experiments were conducted in a deep mine, in a test site region composed of very hard granodiorite with a seismic wave velocity of about 6.0 km/sec and a uniaxial compressive strength, uniaxial tensile strength, and Young`s modulus of 300 MPa, 12 MPa, and 73 GPa, respectively. The blasting design was for a test tunnel excavation of 8 m{sup 2} in cross section, with an advance per round of 2.5 m. Five rounds were performed, each with a large-hole cut and perimeter holes in a 0.4-m spacing charged with 20-mm-diameter water gel explosive to obtain low charge concentration. EDs were used in the holes on the perimeter of the right half, and PDs were used in all other holes. Following each shot, the cross section was measured by laser to determine amount of overbreak and surface smoothness. In situ seismic prospecting was used to estimate the depth of damage in the remaining rock, and the damage was further investigated by boring into both side walls.

Yamamoto, Masaaki [Asahi Chemical Industry Co., Ltd. (Japan); Ichijo, Toshiyuki; Tanaka, Yoshiharu

1995-12-31

159

Characterizing Detonator Output Using Dynamic Witness Plates  

NASA Astrophysics Data System (ADS)

A sub-microsecond, time-resolved micro-particle-image velocimetry (PIV) system is developed to investigate the output of explosive detonators. Detonator output is directed into a transparent solid that serves as a dynamic witness plate and instantaneous shock and material velocities are measured in a two-dimensional plane cutting through the shock wave as it propagates through the solid. For the case of unloaded initiators (e.g. exploding bridge wires, exploding foil initiators, etc.) the witness plate serves as a surrogate for the explosive material that would normally be detonated. The velocity-field measurements quantify the velocity of the shocked material and visualize the geometry of the shocked region. Furthermore, the time-evolution of the velocity-field can be measured at intervals as small as 10 ns using the PIV system. Current experimental results of unloaded exploding bridge wire output in polydimethylsiloxane (PDMS) witness plates demonstrate 20 MHz velocity-field sampling just 300 ns after initiation of the wire.

Murphy, Michael J.; Adrian, Ronald J.

2009-12-01

160

Detonator-activated ball shutter  

DOEpatents

A detonator-activated ball shutter for closing an aperture in about 300.mu. seconds. The ball shutter containing an aperture through which light, etc., passes, is closed by firing a detonator which propels a projectile for rotating the ball shutter, thereby blocking passage through the aperture.

McWilliams, Roy A. (Livermore, CA); von Holle, William G. (Livermore, CA)

1983-01-01

161

Direct Simulation of Pathological Detonations  

Microsoft Academic Search

In previous papers we have demonstrated how the direct simulation Monte Carlo method can be used to simulate detonations. Those simulations were limited to exothermic reactions. In this paper exothermic and endothermic reactions are simulated. Under these circumstances, one obtains pathological detonations. That is, these simulations cannot be predicted using the well-known Chapman-Jouguet hypothesis. The details of these simulations can

James B. Anderson; Lyle N. Long

2003-01-01

162

Propulsive Performances of Pulsed Detonations  

Microsoft Academic Search

The propulsive potential of a reactive mixture that uses detonation as a combustion process is studied. An experimental set up is built up to determine the thrust and the impulse developed in single and multi-operating cycles by the detonation products of a reactive mixture contained in a cylindrical combustion chamber (CC). One end of the CC, called the thrust wall

R. ZITOUN; D. DESBORDES

1999-01-01

163

Semiconductor bridge (SCB) detonator  

DOEpatents

The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge (SCB) igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length. 3 figs.

Bickes, R.W. Jr.; Grubelich, M.C.

1999-01-19

164

Pulse Detonation Engine Modeled  

NASA Technical Reports Server (NTRS)

Pulse Detonation Engine Technology is currently being investigated at Glenn for both airbreathing and rocket propulsion applications. The potential for both mechanical simplicity and high efficiency due to the inherent near-constant-volume combustion process, may make Pulse Detonation Engines (PDE's) well suited for a number of mission profiles. Assessment of PDE cycles requires a simulation capability that is both fast and accurate. It should capture the essential physics of the system, yet run at speeds that allow parametric analysis. A quasi-one-dimensional, computational-fluid-dynamics-based simulation has been developed that may meet these requirements. The Euler equations of mass, momentum, and energy have been used along with a single reactive species transport equation, and submodels to account for dominant loss mechanisms (e.g., viscous losses, heat transfer, and valving) to successfully simulate PDE cycles. A high-resolution numerical integration scheme was chosen to capture the discontinuities associated with detonation, and robust boundary condition procedures were incorporated to accommodate flow reversals that may arise during a given cycle. The accompanying graphs compare experimentally measured and computed performance over a range of operating conditions for a particular PDE. Experimental data were supplied by Fred Schauer and Jeff Stutrud from the Air Force Research Laboratory at Wright-Patterson AFB and by Royce Bradley from Innovative Scientific Solutions, Inc. The left graph shows thrust and specific impulse, Isp, as functions of equivalence ratio for a PDE cycle in which the tube is completely filled with a detonable hydrogen/air mixture. The right graph shows thrust and specific impulse as functions of the fraction of the tube that is filled with a stoichiometric mixture of hydrogen and air. For both figures, the operating frequency was 16 Hz. The agreement between measured and computed values is quite good, both in terms of trend and magnitude. The error is under 10 percent everywhere except for the thrust value at an equivalence ratio of 0.8 in the left figure, where it is 14 percent. The simulation results shown were made using 200 numerical cells. Each cycle of the engine, approximately 0.06 sec, required 2.0 min of CPU time on a Sun Ultra2. The simulation is currently being used to analyze existing experiments, design new experiments, and predict performance in propulsion concepts where the PDE is a component (e.g., hybrid engines and combined cycles).

Paxson, Daniel E.

2001-01-01

165

Pulse Detonation Rocket Magnetohydrodynamic Power Experiment  

NASA Technical Reports Server (NTRS)

The production of onboard electrical power by pulse detonation engines is problematic in that they generate no shaft power; however, pulse detonation driven magnetohydrodynamic (MHD) power generation represents one intriguing possibility for attaining self-sustained engine operation and generating large quantities of burst power for onboard electrical systems. To examine this possibility further, a simple heat-sink apparatus was developed for experimentally investigating pulse detonation driven MHD generator concepts. The hydrogen oxygen fired driver was a 90 cm long stainless steel tube having a 4.5 cm square internal cross section and a short Schelkin spiral near the head end to promote rapid formation of a detonation wave. The tube was intermittently filled to atmospheric pressure and seeded with a CsOH/methanol prior to ignition by electrical spark. The driver exhausted through an aluminum nozzle having an area contraction ratio of A*/A(sub zeta) = 1/10 and an area expansion ratio of A(sub zeta)/A* = 3.2 (as limited by available magnet bore size). The nozzle exhausted through a 24-electrode segmented Faraday channel (30.5 cm active length), which was inserted into a 0.6 T permanent magnet assembly. Initial experiments verified proper drive operation with and without the nozzle attachment, and head end pressure and time resolved thrust measurements were acquired. The exhaust jet from the nozzle was interrogated using a polychromatic microwave interferometer yielding an electron number density on the order of 10(exp 12)/cm at the generator entrance. In this case, MHD power generation experiments suffered from severe near-electrode voltage drops and low MHD interaction; i.e., low flow velocity, due to an inherent physical constraint on expansion with the available magnet. Increased scaling, improved seeding techniques, higher magnetic fields, and higher expansion ratios are expected to greatly improve performance.

Litchford, R. J.; Jones, J. E.; Dobson, C. C.; Cole, J. W.; Thompson, B. R.; Plemmons, D. H.; Turner, M. W.

2003-01-01

166

On Gas Flow Circulation in Detonator Delay Elements  

Microsoft Academic Search

We study theoretically the pressure and gas flow fields produced by a deflagration wave as it passes down a cylindrical detonator delay element filled with a porous pyrotechnic. We model the flame front as a planar source of heat and gas which travels down the element with constant speed, thus eliminating the detailed chemistry of the reaction. It is shown

J. A. KING-HELE; J. WILLIAMS

2000-01-01

167

Simulations of Pulse Detonation Engine Reactive Flow Processes  

Microsoft Academic Search

The present computational study involves one- and two- dimensional simulations of the pulse detonation wave engine or PDE. Alternative engine configurations, with and without the presence of nozzles of varying shapes, are explored. Effects of configuration geometry on engine performance parameters as well as noise generation are quantified. Noise estimates account for modes generated by the PDE cycle itself as

Xing He; Ann R. Karagozian

2002-01-01

168

DEtonation gas delivery unit  

SciTech Connect

The detonation gas for gas-detonatable blasting charges used in surface mining and the like is supplied by a portable self-contained delivery unit connected to the blasting charges by a network of small flexible tubing, which unit blends pressurized fuel and oxidizing gases from separate supply sources in predetermined proportions and regulates the separate flows of such gases in response to the backpressure imposed by the tubing network to maintain such proportions in the gas blend delivered to the tubing network. The separate gas flows are controlled by servo-actuated flow control valves actuated by a control gas pressure which is applied or released in response to such backpressure. Preferably, the control gas pressure is regulated by a pair of pilot valves, one normally open and the other normally closed, connected in parallel between the servo actuators of such flow control valves and the control gas source and the atmosphere, respectively, the state of the pilot valves being reversed in response to the occurrence of a backpressure exceeding a predetermined maximum to disconnect the control gas from and release the existing gas pressure on the flow control valve servo actuators. A preferred safety feature assures complete filling of the tubing network before the gas therein can be ignited to initiate detonation of the explosive charges.

Emmett, G. C.

1984-12-04

169

Influence of the preheating of a working medium on the thermodynamic efficiency of pulse-detonation-engine propulsion modules  

Microsoft Academic Search

A theoretical substantiation of calculation of the thermodynamic cycle of engines with detonation fuel combustion, which is\\u000a realized in propulsion modules of pulse detonation engines, has been given. A system of equations for calculation of the parameters\\u000a of detonation combustion waves under different conditions of their excitation has been obtained. On their basis, investigations\\u000a of the influence of different factors

Yu. N. Nechaev

2010-01-01

170

The dynamics of unsteady detonation in ozone  

SciTech Connect

An ultra-fine, sub-micron discrete grid is used to capture the unsteady dynamics of a one-dimensional detonation in an inviscid O - O{sub 2} - O{sub 3} mixture. The ultra-fine grid is necessary to capture the length scales revealed by a complementary analysis of the steady detonation wave structure. For the unsteady calculations, shock-fitting coupled with a high order spatio-temporal discretization scheme combine to render numerical corruption negligible. As a result, mathematically verified solutions for a mixture initially of all O{sub 3} at one atmosphere and 298.15 K have been obtained; the solutions are converging at a rate much faster than the sub-first order convergence rate of all shock-capturing schemes. Additionally, the model has been validated against limited experimental data. Transient calculations show that strongly overdriven waves are stable and moderately overdriven waves unstable. New limit cycle behavior is revealed, and the first high resolution bifurcation diagram for etonation with detailed kinetics is found.

Aslam, Tariq D [Los Alamos National Laboratory; Powers, Joseph M [Los Alamos National Laboratory

2008-01-01

171

The role of cellular structure on increasing the detonability limits of three-step chain-branching detonations  

SciTech Connect

In [1], the dynamics of a pulsating three-step chain-branching detonation were studied. The reaction model consists of, sequentially, chain-initiation, chain-branching and chain-termination steps. The chain-initiation and chain-branching steps are taken to be thermally neutral, with chemical energy release occuring in the chain-termination stage. The purpose of the present study is to examine whether cellular detonation structure can increase the value of the chain-branching cross-over temperature T{sub b} at which fully coupled detonation solutions are observed over those in 1 D. The basic concept is straightforward and has been discussed in [1] and [3]; if T{sub s} drops below T{sub b} at the lead shock, the passage of a transverse shock can increase both the lead shock temperature and the temperature behind the transverse wave back above T{sub b}, thus sustaining an unstable cellular detonation for values of T{sub b} for which a one-dimensional pulsating detonation will fail. Experiments potentially supporting this hypothesis with irregular detonations have been shown in [3] in a shock tube with acoustically absorbing walls. Removal of the transverse waves results in detonation failure, giving way to a decoupled shock-flame complex. A number of questions remain to be addressed regarding the possibility of such a mechanism, and, if so, about the precise mechanisms driving the cellular structure for large T{sub b}. For instance, one might ask what sets the cell size in a chain-branching detonation, particularly could the characteristic cell size be set by the chain-branching cross-over temperature T{sub b}: after a transverse wave shock collision, the strength of the transverse wave weakens as it propagates along the front. If the spacing between shock collisions is too large (cell size), then the transverse shocks may weaken to the extent that the lead shock temperature or that behind the transverse waves is not raised above T{sub b}, losing chemical energy to drive the front in those regions. Failure may result if less than sufficient of the lead shock be driven above n to sustain reaction. Our starting point for generating cellular solutions is as in [I], consisting of an initial ZND wave in the channel, but perturbed here by a density non-uniformity to generate a cellular structure. Exactly how far the detonability limits (value of T{sub b}) can be extended is not addressed here, as such issues relate in part to the way the cellular structure is generated [6]. Our concern here is to investigate the mechanisms of self-sustained cellular detonation for values of T{sub b} above those that lead to 1D pulsating wave failure that can be generated from the initial ZND wave. Finally, we do not consider cellular propagation driven by a process of apparent thermal ignition of hot-spots downstream that tends to appear close to the 20 detonability limit. Such events are subject to the lack of correct thermal diffusive physics in the model and thus to the form of numerical dissipation in the underlying flow algorithm.

Short, Mark [Los Alamos National Laboratory; Kiyanda, Charles B [Los Alamos National Laboratory; Quirk, James J [Los Alamos National Laboratory; Sharpe, Gary J [UNIV OF LEEDS, UK

2011-01-27

172

The influence of structural response on sympathetic detonation  

NASA Technical Reports Server (NTRS)

The role that a munition's structural response plays in the ignition process and the development of violent reactions and detonations is explored. The munition's structural response is identified as one of the factors that influences reaction violence. If the structural response of a round is known, this knowledge can be used to redstruce the probability that a large explosion would result from the sequential detonation of individual rounds within a large storage array. The response of an acceptor round was studied. The castings fail in the same manner regardless of whether or not there is a fill material present in the round. These failures are caused by stress waves which are transformed from compressive waves to tensile waves by reflection as the impact energy moves around the casting. Since these waves move in opposite directions around the projectile circumference and collide opposite the point of impact, very high tensile forces are developed which can crack the casing.

Watson, J. L.

1980-01-01

173

Preparation of C60 by Detonation Technique  

NASA Astrophysics Data System (ADS)

A mixture of TNT (Trinitrotoluene) and natural graphite was detonated in a vacuum container which was immersed into cooling water; detonation products were collected for detecting. The results of mass spectroscopy, high performance liquid chromatography showed significant signals of C60, which proved that C60 could be synthesized by detonating the mixture of TNT/graphite and the detonation pressure was around 12.3 GPa and the detonation temperature was around 1985 K.

Wei, Xianfeng; Han, Yong; Long, Xinping

2012-11-01

174

Quantitative Studies of Detonator Performance  

NASA Astrophysics Data System (ADS)

Detonators are widely used in explosive applications, with commercial systems being mass produced from a number of suppliers. One issue that affects producers and users is the reproducibility and output of the explosive system. This can be considered from both the component parts and as the fully assembled detonator. This paper outlines a simple experimental system for measuring the output of detonators or small amounts of explosive. The basis of the technique was pioneered by Bertram Hopkinson in the early 20th Century, here the fundamental idea is applied with advanced instrumentation to both calibrate the system and show its potential for use in both fundamental and applied research.

Mott, J.; Collins, A. L.; Proud, W. G.

2009-12-01

175

Detonation tube impulse in sub-atmospheric environments.  

SciTech Connect

The thrust from a multi-cycle, pulse detonation engine operating at practical flight altitudes will vary with the surrounding environment pressure. We have carried out the first experimental study using a detonation tube hung in a ballistic pendulum arrangement within a large pressure vessel in order to determine the effect that the environment has on the single-cycle impulse. The air pressure inside the vessel surrounding the detonation tube varied between 100 and 1.4 kPa while the initial pressure of the stoichiometric ethylene-oxygen mixture inside the tube varied between 100 and 30 kPa. The original impulse model (Wintenberger et al., Journal of Propulsion and Power, Vol. 19, No. 1, 2002) was modified to predict the observed increase in impulse and blow down time as the environment pressure decreased below one atmosphere. Comparisons between the impulse from detonation tubes and ideal, steady flow rockets indicate incomplete expansion of the detonation tube exhaust, resulting in a 37% difference in impulse at a pressure ratio (ratio of pressure behind the Taylor wave to the environment pressure) of 100.

Cooper, Marcia A.; Shepherd, Joseph E. (California Institute of Technology, Pasadena, CA)

2005-04-01

176

Theory of interactions of thin strong detonations with turbulent gases  

NASA Astrophysics Data System (ADS)

We present the exact small-amplitude linear Laplace-transform theory describing the propagation of an initially planar detonation front through a gaseous mixture with nonuniform density perturbations, complementing earlier normal-mode results for nonuniform velocity perturbations. The investigation considers the fast-reaction limit in which the detonation thickness is much smaller than the size of the density perturbations, so that the detonation can be treated as an infinitesimally thin front with associated jump conditions given by the Rankine-Hugoniot equations. The analytical development gives the exact transient evolution of the detonation front and the associated disturbance patterns generated behind for a single-mode density field, including explicit expressions for the distributions of density, pressure, and velocity. The results are then used in a Fourier analysis of the detonation interaction with two-dimensional and three-dimensional isotropic density fields to provide integral formulas for the kinetic energy, enstrophy, and density amplification. Dependencies of the solution on the heat-release parameter and propagation Mach number are discussed, along with differences and similarities with results of previous analyses for non-reacting shock waves.

Huete, César; Sánchez, Antonio L.; Williams, Forman A.

2013-07-01

177

Experimental Study of Ignition and Detonation Initiation in Two-Phase Valveless Pulse Detonation Engines  

Microsoft Academic Search

This paper addressed the ignition and detonation initiation investigation of two-phase valveless pulse detonation engines (PDEs) in different operational cases. To quantify the ignition and detonation initiation performance, the parameters detonation initiation time and deflagration-to-detonation transition (DDT) distance were examined. Detonation initiation time was defined as the time between the times when the spark plug received the ignition signal and

Zhiwu Wang; Chuanjun Yan; Longxi Zheng; Wei Fan

2009-01-01

178

New generation detonics  

SciTech Connect

Modern theory is being used to accelerate the development of new high performance explosive molecules. Combining quantum chemistry calculations with synthesis of promising candidate molecules may enable the advance of the state of the art in this field by more than 50 years. We have established a high explosive performance prediction code by linking the thermochemical code CHEETAH with the ab initio electronic structure code GAUSSIAN and the molecular packing code MOLPAK. GAUSSIAN is first used to determine the shape of the molecule and its binding energy; the molecules are then packed together into a low energy configuration by MOLPAK. Finally, CHEETAH is used to transform the crystal energy and density into explosive performance measures such as detonation velocity, pressure, and energy. Over 70 target molecules have been created, and several of these show promise in combining performance, chemical stability, and ease of synthesis.

Souers, P.C.

1996-12-15

179

Detonation initiation of JP-8-oxygen mixtures at different initial temperatures  

NASA Astrophysics Data System (ADS)

Liquid fuel with sufficient vapor proportion at micron scale is essentially required to increase specific energy density and reduce volume requirements for application of pulse detonation engine. For JP-8, the fully vaporized temperature ranges from 380 to 410 K. In this study, the fuel vapor with oxygen is not enough to induce the reaction and leads to failure of detonation initiation at the initial temperature of 373 K. Condensed fuel was also observed on the bottom of detonation tube. At 393 K, the detonation wave was successfully generated even though a portion of fuel was in a liquid state. The deflagration-to-detonation run-up distance and the pressure trace at fully vaporized conditions, in which the initial temperatures were at 413, 433, and 453 K, were similar to those of gaseous mixtures, such as propane-oxygen mixture.

Wen, C.-S.; Chung, K.-M.; Lai, W.-H.

2012-09-01

180

Advanced modeling of detonation dynamics in energetic materials and explosive systems  

NASA Astrophysics Data System (ADS)

Explosives are energetic materials that support a supersonic detonation wave; a shock followed by an exothermic reaction zone. Because the explosive products expand rapidly behind the shock, the flow can choke. A sonic (characteristic) surface forms that propagates at about the same velocity as the lead shock, sealing the reaction zone from the trailing flow. Since detonation propagates in autonomous and robust way and induces large pressure changes (hundreds of Kilo bars for condensed explosives), they are useful for engineering purposes. The explosive system is detonation in the explosive and its interaction with its environment. Explosive systems include material processing, for example. Extreme miniaturized explosive systems have many alternative applications that include prospects for bio-medical uses. Since the detonation reaction zone is extremely thin compared to the domain in which it propagates, the calculation of detonation dynamics is a difficult multi-scale problem. Direct numerical simulation of the behavior of detonation dynamics is usually not an option. Fortunately, the scale disparity allows asymptotic treatments of the detonation front, and these have led to a rich and interesting theory of detonation shock dynamics where one obtains evolution equations for the front that are geometric in character and that relate the normal detonation shock velocity to the shock front curvature and higher intrinsic derivatives. Detonations exhibit generic instabilities that include pulsations and cellular instabilities; some of these can be described by the asymptotic theory. The theory of detonation shock dynamics has provided new way to interpret experiments and measure the properties of condensed explosives. Validation of theory with experiments requires multi-material (fluid) simulation of the interaction of the explosive with inert materials. The use of modern high-resolution numerical methods and modern material interface treatments, such as level-set methods is required. The talk will summarize some key advances in this subject.

Stewart, D. Scott

2006-11-01

181

An Investigation, By the Method of Characteristics, Of the Lateral Expansion of the Gases behind a Detonating Slab of Explosive  

Microsoft Academic Search

The phenomena occurring when an uncased explosive charge is detonated in a fluid medium are examined by hydrodynamical methods. Attention is focused chiefly on the pressure and velocity distributions in the gaseous products of the explosion, which expand laterally behind the detonation wave as it travels down the charge, the results being shown in graphical form. To simplify the problem,

R. Hill; D. C. Pack

1947-01-01

182

ANALYSIS OF PULSE DETONATION TURBOJET ENGINES RONNACHAI VUTTHIVITHAYARAK  

E-print Network

ANALYSIS OF PULSE DETONATION TURBOJET ENGINES by RONNACHAI VUTTHIVITHAYARAK Presented, in both Thailand and the United States. August 25, 2011 iii #12;ABSTRACT ANALYSIS OF PULSE DETONATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3.1 Detonation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3.2 Pulse Detonation

Texas at Arlington, University of

183

Development and qualification testing of a laser-ignited, all-secondary (DDT) detonator  

NASA Technical Reports Server (NTRS)

The Indian Head Division, Naval Surface Warfare Center (IHDIV, NSWC) is conducting a qualification program for a laser-ignited, all-secondary (DDT) explosive detonator. This detonator was developed jointly by IHDIV, NSWC and the Department of Energy's EG&G Mound Applied Technologies facility in Miamisburg, Ohio to accept a laser initiation signal and produce a fully developed shock wave output. The detonator performance requirements were established by the on-going IHDIV, NSWC Laser Initiated Transfer Energy Subsystem (LITES) advanced development program. Qualification of the detonator as a component utilizing existing military specifications is the selected approach for this program. The detonator is a deflagration-to-detonator transfer (DDT) device using a secondary explosive, HMX, to generate the required shock wave output. The prototype development and initial system integration tests for the LITES and for the detonator were reported at the 1992 International Pyrotechnics Society Symposium and at the 1992 Survival and Flight Equipment National Symposium. Recent results are presented for the all-fire sensitivity and qualification tests conducted at two different laser initiation pulses.

Blachowski, Thomas J.; Krivitsky, Darrin Z.; Tipton, Stephen

1994-01-01

184

A numerical study of the mechanisms of self-reignition in low-overdrive detonations  

NASA Astrophysics Data System (ADS)

Below a threshold in overdrive, both stability analysis and numerical simulations predict that one-dimensional detonations in high activation energy mixtures behave as a chaotic sequence of failures followed by reignition. Instead, less chaotic, cellular detonations almost invariably occur in experiments. Numerical simulation, based on the Euler equations with single step chemistry, shows that a ZND detonation initially fails in that regime. The detonation splits into a weaker shock, a surface discontinuity separating reacted from unreacted fluid, and a rarefaction wave. However, the detonation is eventually reignited by the explosion of a small gas pocket, in a process reminiscent of deflagration to detonation transition. In the fluid heated by the leading shock, the chemical reaction occurs slowly at first, but becomes faster as heat is released, until the pocket explodes. Small differences in initial temperature result in large enough differences in reaction time sufficient for one pocket of fluid to explode. In two dimensions, the explosion occurs earlier because an oblique shock structure develops which unevenly heats the fluid that passes through the leading shock. Hence, pockets that underwent more heating will explode sooner. As it moves upstream, the two-dimensional explosion, meets the leading shock and the detonation quickly develops a transverse wave structure.

Williams, D. N.; Bauwens, L.; Oran, E. S.

1996-07-01

185

Detonation of insensitive high explosives by a Q-switched ruby laser.  

NASA Technical Reports Server (NTRS)

Immediate longitudinal detonations have been observed in confined small-diameter columns of PETN, RDX, and tetryl by using a focused Q-switched ruby laser. The energy ranged from 0.8 to 4.0 J in a pulse width of 25 nsec. A 1000-A-thick aluminum film deposited on a glass window was used to generate a shock wave at the window-explosive interface when irradiated by the laser. In some cases, steady-state detonations were reached in less than .5 microsec with less than 10% variation in the detonation velocity.

Yang, L. C.; Menichelli, V. J.

1971-01-01

186

Use of Gas Detonation in a Controlled Frequency Mode (Review)  

Microsoft Academic Search

Research problems arising in the development of various devices with the use of detonation in a controlled frequency mode (pulsed detonation) are considered. The frequency of cycles can be varied by independent initiation of detonation by a controlled system of ignition. Problems of detonation initiation concerning the frequency mode are considered: direct initiation, deflagration-to-detonation transition, and transition of a detonation

T. V. Bazhenova; V. V. Golub

2003-01-01

187

Theoretical analysis of rotating two phase detonation in a rocket motor  

NASA Technical Reports Server (NTRS)

Tangential mode, non-linear wave motion in a liquid propellant rocket engine is studied, using a two phase detonation wave as the reaction model. Because the detonation wave is followed immediately by expansion waves, due to the side relief in the axial direction, it is a Chapman-Jouguet wave. The strength of this wave, which may be characterized by the pressure ratio across the wave, as well as the wave speed and the local wave Mach number, are related to design parameters such as the contraction ratio, chamber speed of sound, chamber diameter, propellant injection density and velocity, and the specific heat ratio of the burned gases. In addition, the distribution of flow properties along the injector face can be computed. Numerical calculations show favorable comparison with experimental findings. Finally, the effects of drop size are discussed and a simple criterion is found to set the lower limit of validity of this strong wave analysis.

Shen, I.; Adamson, T. C., Jr.

1973-01-01

188

Detonation in TATB Hemispheres  

SciTech Connect

Streak camera breakout and Fabry-Perot interferometer data have been taken on the outer surface of 1.80 g/cm{sup 3} TATB hemispherical boosters initiated by slapper detonators at three temperatures. The slapper causes breakout to occur at 54{sup o} at ambient temperatures and 42{sup o} at -54 C, where the axis of rotation is 0{sup o}. The Fabry velocities may be associated with pressures, and these decrease for large timing delays in breakout seen at the colder temperatures. At room temperature, the Fabry pressures appear constant at all angles. Both fresh and decade-old explosive are tested and no difference is seen. The problem has been modeled with reactive flow. Adjustment of the JWL for temperature makes little difference, but cooling to -54 C decreases the rate constant by 1/6th. The problem was run both at constant density and with density differences using two different codes. The ambient code results show that a density difference is probably there but it cannot be quantified.

Druce, B; Souers, P C; Chow, C; Roeske, F; Vitello, P; Hrousis, C

2004-03-17

189

APPLICATION OF FUEL BLENDS FOR ACTIVE DETONATION CONTROL IN A PULSED DETONATION ENGINE  

Microsoft Academic Search

Reliable operation of a pulsed detonation engine (PDE) can be attained by adopting a controlled charge concept based on the in-chamber blending of several fuels exhibiting different detonability. Detonability of fuels is characterized by the Octane Number. For examining Octane Number requirements of a PDE, dealing with fuel detonability and resistance to premature ignition, a semi-empirical oxidation mechanism for hydrogen

S. M. Frolov

190

Detonation propagation and Mach stem formation in PBXN-9  

SciTech Connect

PBXN-9 is an explosive that is less sensitive to certain insults, yet retains a high level of performance. As a result, PBXN-9 has been considered as an interim insensitive high explosive for conventional munitions systems. Certain of these systems incorporate wave control methodologies that require some form of reactive flow representation to achieve accurate predictions of the wave propagation. The authors have continued the use of Detonation Shock Dynamics (DSD) as a means to approximately account for reactive flow effects, yet retain the efficiency necessary for the munitions design process. To use DSD, they have taken the approach to calibrate explosives by measuring the detonation velocity as a function of local wave curvature. The DSD calibration, including the appropriate boundary conditions, can then be used to predict wave propagation in complex situations such as around obstacles, following wave-wave collisions, and so on. This paper describes the DSD calibration for PBXN-9, along with the methodologies used to obtain it, for both convergent and divergent flow (positive and negative wave curvatures). During the course of the calibration for convergent flow, Mach stem formation is observed in wave reflection experiments. The characteristics of the Mach stem formation and the subsequent growth are analyzed, presented and compared to similar measurements on other explosives. Illustrative examples of the use of DSD to predict wave propagation are provided.

Hull, L.M.

1997-09-01

191

DSD front models : nonideal explosive detonation  

SciTech Connect

The Detonation Shock Dynamics (DSD) method for propagating detonation in numerical simulation of detonation in high explosive (HE) is based on three elements: (1) a subscale theory of multi-dimensional detonation that treats the evolving detonation as a front with dynamics that depends only on metrics of the front (such as curvature, etc.), (2) high-resolution direct numerical sirnuliltion of detonation serving both to test existing subscale theories and suggest modifications, and (3) physical experiments to characterize multi-dimensional detonation propagation on real explosives and to calibrate the front models for use in engineering simulations. In this paper we describe our work on all three of these elements of the DSD method as it applies to detonation in nonideal explosives.

Bdzil, J. B. (John Bohdan); Short, M. (Mark Short); Aslam, T. D. (Tariq D.); Catanach, R. A. (Richard A.); Hill, L. G. (Larry G.)

2001-01-01

192

Numerical study of chemically reacting viscous flow relevant to pulsed detonation engines  

NASA Astrophysics Data System (ADS)

A computational fluid dynamics code for two-dimensional, multi-species, laminar Navier-Stokes equations is developed to simulate a recently proposed engine concept for a pulsed detonation based propulsion system and to investigate the feasibility of the engine of the concept. The governing equations that include transport phenomena such as viscosity, thermal conduction and diffusion are coupled with chemical reactions. The gas is assumed to be thermally perfect and in chemically non-equilibrium. The stiffness due to coupling the fluid dynamics and the chemical kinetics is properly taken care of by using a time-operator splitting method and a variable coefficient ordinary differential equation solver. A second-order Roe scheme with a minmod limiter is explicitly used for space descretization, while a second-order, two-step Runge-Kutta method is used for time descretization. In space integration, a finite volume method and a cell-centered scheme are employed. The first-order derivatives in the equations of transport properties are discretized by a central differencing with Green's theorem. Detailed chemistry is involved in this study. Two chemical reaction mechanisms are extracted from GRI-Mech, which are forty elementary reactions with thirteen species for a hydrogen-air mixture and twenty-seven reactions with eight species for a hydrogen-oxygen mixture. The code is ported to a high-performance parallel machine with Message-Passing Interface. Code validation is performed with chemical kinetic modeling for a stoichiometric hydrogen-air mixture, an one-dimensional detonation tube, a two-dimensional, inviscid flow over a wedge and a viscous flow over a flat plate. Detonation is initiated using a numerically simulated arc-ignition or shock-induced ignition system. Various freestream conditions are utilized to study the propagation of the detonation in the proposed concept of the engine. Investigation of the detonation propagation is performed for a pulsed detonation rocket and a supersonic combustion chamber. For a pulsed detonation rocket case, the detonation tube is embedded in a mixing chamber where an initiator is added to the main detonation chamber. Propagating detonation waves in a supersonic combustion chamber is investigated for one- and two-dimensional cases. The detonation initiated by an arc and a shock wave is studied in the inviscid and viscous flow, respectively. Various features including a detonation-shock interaction, a detonation diffraction, a base flow and a vortex are observed.

Yi, Tae-Hyeong

2005-11-01

193

Pulse Detonation Rocket MHD Power Experiment  

NASA Technical Reports Server (NTRS)

A pulse detonation research engine (MSFC (Marshall Space Flight Center) Model PDRE (Pulse Detonation Rocket Engine) G-2) has been developed for the purpose of examining integrated propulsion and magnetohydrodynamic power generation applications. The engine is based on a rectangular cross-section tube coupled to a converging-diverging nozzle, which is in turn attached to a segmented Faraday channel. As part of the shakedown testing activity, the pressure wave was interrogated along the length of the engine while running on hydrogen/oxygen propellants. Rapid transition to detonation wave propagation was insured through the use of a short Schelkin spiral near the head of the engine. The measured detonation wave velocities were in excess of 2500 m/s in agreement with the theoretical C-J velocity. The engine was first tested in a straight tube configuration without a nozzle, and the time resolved thrust was measured simultaneously with the head-end pressure. Similar measurements were made with the converging-diverging nozzle attached. The time correlation of the thrust and head-end pressure data was found to be excellent. The major purpose of the converging-diverging nozzle was to configure the engine for driving an MHD generator for the direct production of electrical power. Additional tests were therefore necessary in which seed (cesium-hydroxide dissolved in methanol) was directly injected into the engine as a spray. The exhaust plume was then interrogated with a microwave interferometer in an attempt to characterize the plasma conditions, and emission spectroscopy measurements were also acquired. Data reduction efforts indicate that the plasma exhaust is very highly ionized, although there is some uncertainty at this time as to the relative abundance of negative OH ions. The emission spectroscopy data provided some indication of the species in the exhaust as well as a measurement of temperature. A 24-electrode-pair segmented Faraday channel and 0.6 Tesla permanent magnet assembly were then installed on Marshall Space Flight Center's (MSFC's) rectangular channel pulse detonation research engine. Magnetohydrodynamic (MHD) electrical power extraction experiments were carried out for a range of load impedances in which cesium hydroxide seed (dissolved in methanol) was sprayed into the gaseous oxygen/hydrogen propellants. Positive power extraction was obtained, but preliminary analysis of the data indicated that the plasma electrical conductivity is lower than anticipated and the near-electrode voltage drop is not negligible. It is believed that the electrical conductivity is reduced due to a large population of negative OH ions. This occurs because OH has a strong affinity for capturing free electrons. The effect of near-electrode voltage drop is associated with the high surface-to-volume ratio of the channel (1-inch by 1-inch cross-section) where surface effects play a dominant role. As usual for MHD devices, higher performance will require larger scale devices. Overall, the gathered data is extremely valuable from the standpoint of understanding plasma behavior and for developing empirical scaling laws.

Litchford, Ron J.; Cook, Stephen (Technical Monitor)

2002-01-01

194

Environmentally Benign Stab Detonators  

SciTech Connect

The coupling of energetic metallic multilayers (a.k.a. flash metal) with energetic sol-gel synthesis and processing is an entirely new approach to forming energetic devices for several DoD and DOE needs. They are also practical and commercially viable manufacturing techniques. Improved occupational safety and health, performance, reliability, reproducibility, and environmentally acceptable processing can be achieved using these methodologies and materials. The development and fielding of this technology will enhance mission readiness and reduce the costs, environmental risks and the necessity of resolving environmental concerns related to maintaining military readiness while simultaneously enhancing safety and health. Without sacrificing current performance, we will formulate new impact initiated device (IID) compositions to replace materials from the current composition that pose significant environmental, health, and safety problems associated with functions such as synthesis, material receipt, storage, handling, processing into the composition, reaction products from testing, and safe disposal. To do this, we will advance the use of nanocomposite preparation via the use of multilayer flash metal and sol-gel technologies and apply it to new small IIDs. This work will also serve to demonstrate that these technologies and resultant materials are relevant and practical to a variety of energetic needs of DoD and DOE. The goal will be to produce an IID whose composition is acceptable by OSHA, EPA, the Clean Air Act, Clean Water Act, Resource Recovery Act, etc. standards, without sacrificing current performance. The development of environmentally benign stab detonators and igniters will result in the removal of hazardous and toxic components associated with their manufacturing, handling, and use. This will lead to improved worker safety during manufacturing as well as reduced exposure of Service personnel during their storage and or use in operations. The implementation of energetic sol-gel coated metallic multilayers, as new small IIDs will result in dramatically reduced environmental risks and improved worker and user safety risks without any sacrifice in the performance of the device. The proposed effort is designed to field an IID that is free of toxic (e.g., tetrazene) and heavy metal constituents (e.g., lead styphnate, lead azide, barium nitrate, and antimony sulfides) present in the NOL-130 initiating mixture and in the lead azide transfer charge of current stab detonators. The preferred materials for this project are nanocomposites consisting of thin foils of metallic multilayers, composed of nanometer thick regions of different metals, coated with a sol-gel derived energetic material. The favored metals for the multilayers will be main-group and early transition metals such as, but not limited to, boron, aluminum, silicon, titanium, zirconium, and nickel. Candidate sol-gel energetic materials include iron (III) oxide/aluminum nanocomposites. It should be noted that more traditional materials than sol-gel might also be used with the flash metals. The metallic multilayers undergo an exothermic transition to a more stable intermetallic alloy with the appropriate mechanical or thermal stimulus. This exothermic transition has sufficient output energy to initiate the more energy dense sol-gel energetic material, or other candidate materials. All of the proposed initiation mix materials and their reaction by products have low toxicity, are safe to handle and dispose of, and provide much less environmental and health concerns than the current composition. We anticipate that the technology and materials proposed here will be produced successfully in production scale with very competitive costs with existing IIDs, when amortized over the production lifetime. The sol-gel process is well known and used extensively in industry for coatings applications. All of the proposed feedstock components are mass-produced and have relatively low costs. The multilayer deposition equipment is commercially available and the technology is wide

Gash, A E

2006-07-07

195

Fiber Bragg grating sensing of detonation and shock experiments at Los Alamos National Laboratory  

NASA Astrophysics Data System (ADS)

An all optical-fiber-based approach to measuring high explosive detonation front position and velocity is described. By measuring total light return using an incoherent light source reflected from a fiber Bragg grating sensor in contact with the explosive, dynamic mapping of the detonation front position and velocity versus time is obtained. We demonstrate two calibration procedures and provide several examples of detonation front measurements: PBX 9502 cylindrical rate stick, radial detonation front in PBX 9501, and PBX 9501 detonation along a curved meridian line. In the cylindrical rate stick measurement, excellent agreement with complementary diagnostics (electrical pins and streak camera imaging) is achieved, demonstrating accuracy in the detonation front velocity to below the 0.3% level when compared to the results from the pin data. In a similar approach, we use embedded fiber grating sensors for dynamic pressure measurements to test the feasibility of these sensors for high pressure shock wave research in gas gun driven flyer plate impact experiments. By applying well-controlled steady shock wave pressure profiles to soft materials such as PMMA, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave. Comparison of the fiber sensor results is then made with traditional methods (velocimetry and electro-magnetic particle velocity gauges) to gauge the accuracy of the approach.

Rodriguez, G.; Sandberg, R. L.; Jackson, S. I.; Dattelbaum, D. M.; Vincent, S. W.; McCulloch, Q.; Martinez, R. M.; Gilbertson, S. M.; Udd, E.

2013-05-01

196

PERFORMANCE ENHANCEMENTS ON A PULSED DETONATION ROCKET  

E-print Network

PERFORMANCE ENHANCEMENTS ON A PULSED DETONATION ROCKET The members of the Committee approve #12;To Grandma and Grandpa #12;PERFORMANCE ENHANCEMENTS ON A PULSED DETONATION ROCKET by JASON MATTHEW into an intermittent pulsed detonation device. Results show signi¯cant improvements in comparison to cases without

Texas at Arlington, University of

197

PARAMETRIC CYCLE ANALYSIS FOR PULSE DETONATION ENGINES  

E-print Network

PARAMETRIC CYCLE ANALYSIS FOR PULSE DETONATION ENGINES by HAIDER HEKIRI Presented to the Faculty, in particular, pulse detonation engines. Dr. Wilson taught me the basics of propulsion and made me enjoy #12;iii ABSTRACT PARAMETRIC CYCLE ANALYSIS FOR PULSE DETONATION ENGINES Publication No. ______ Haider

Texas at Arlington, University of

198

Reaction zone structure for strong, weak overdriven, and weak underdriven oblique detonations  

NASA Technical Reports Server (NTRS)

A simple dynamic systems analysis is used to give examples of strong, weak overdriven, and weak underdriven oblique detonations. Steady oblique detonations consisting of a straight lead shock attached to a solid wedge followed by a resolved reaction zone structure are admitted as solutions to the reactive Euler equations. This is demonstrated for a fluid that is taken to be an inviscid, calorically perfect ideal gas that undergoes a two-step irreversible reaction with the first step exothermic and the second step endothermic. This model admits solutions for a continuum of shock wave angles for two classes of solutions identified by a Rankine-Hugoniot analysis: strong and weak overdriven waves. The other class, weak underdriven, is admitted for eigenvalue shock-wave angles. Chapman-Jouguet waves, however, are not admitted. These results contrast those for a corresponding onestep model that, for detonations with a straight lead shock, only admits strong, weak overdriven, and Chapman-Jouguet solutions.

Powers, Joseph M.; Gonthier, Keith A.

1992-01-01

199

The development and testing of pulsed detonation engine ground demonstrators  

NASA Astrophysics Data System (ADS)

The successful implementation of a PDE running on fuel and air mixtures will require fast-acting fuel-air injection and mixing techniques, detonation initiation techniques such as DDT enhancing devices or a pre-detonator, an effective ignition system that can sustain repeated firing at high rates and a fast and capable, closed-loop control system. The control system requires high-speed transducers for real-time monitoring of the PDE and the detection of the detonation wave speed. It is widely accepted that the detonation properties predicted by C-J detonation relations are fairly accurate in comparison to experimental values. The post-detonation flow properties can also be expressed as a function of wave speed or Mach number. Therefore, the PDE control system can use C-J relations to predict the post-detonation flow properties based on measured initial conditions and compare the values with those obtained from using the wave speed. The controller can then vary the initial conditions within the combustor for the subsequent cycle, by modulating the frequency and duty cycle of the valves, to obtain optimum air and fuel flow rates, as well as modulate the energy and timing of the ignition to achieve the required detonation properties. Five different PDE ground demonstrators were designed, built and tested to study a number of the required sub-systems. This work presents a review of all the systems that were tested, along with suggestions for their improvement. The PDE setups, ranged from a compact PDE with a 19 mm (3/4 in.) i.d., to two 25 mm (1 in.) i.d. setups, to a 101 mm (4 in.) i.d. dual-stage PDE setup with a pre-detonator. Propane-oxygen mixtures were used in the smaller PDEs. In the dual-stage PDE, propane-oxygen was used in the pre-detonator, while propane-air mixtures were used in the main combustor. Both rotary valves and solenoid valve injectors were studied. The rotary valves setups were tested at 10 Hz, while the solenoid valves were tested at up to 30 Hz on a 25 mm i.d. PDE. The dual-stage PDE was run at both 1 Hz and 10 Hz using solenoid valves. The two types of valves have their drawbacks and advantages which are discussed, along with ways to enhance their functionality. Rotary valves with stepper motor drives are recommended to be used for air flow control, while an array of solenoid injectors may be used for liquid or gaseous fuel injection. Various DDT enhancing devices were tested, including Shchelkin spirals (with varying thicknesses, lengths and pitches), grooved sleeves and converging-diverging nozzles. The Shchelkin spirals are found to be the most effective of all, at blockage ratios in the region of 50 to 55%. To improve the durability of Shchelkin spirals, it is recommended that they be grooved into the inside of tubes or inserted as replaceable sleeves. Orifice plates with high blockage ratios, in the region of 50 to 80%, are also recommended due to their simple and rugged design. All these devices along with the PDE combustor will require a strong cooling system to prevent damage from the extreme detonation temperatures. High energy (HE) and low energy (LE) ignition systems were tested and compared along with various designs of igniters and automotive spark plugs. It is concluded that while HE ignition may help unsensitized fuel-air mixtures to achieve detonations faster than LE systems, the former have severe drawbacks. The HE igniters get damaged quickly, and require large and heavy power supplies. While the HE ignition is able to reduce ignition delay in a propane-oxygen pre-detonator, it did not show a significant improvement in bringing about DDT in the main combustor using propane-air mixtures. The compact pre-detonator design with a gradual area change transitioning to a larger combustor is found to be effective for detonation initiation, but the pre-detonator concept is recommended for high-speed applications only, since higher speeds requires more sensitive, easily detonable fuels that have short ignition delays and DDT run-up distances. Dynamic pressure transducers, ion detectors and p

Panicker, Philip Koshy

2008-10-01

200

Reaction Processes and Nozzle Effects in Pulse Detonation Engines  

Microsoft Academic Search

The present study involves numerical simulations of the pulse detonation wave engine, or PDE, with specific focus on the effects of alternative nozzle geometries, both divergent and convergent. Two-dimensional as well as quasi-one-dimensional simulations are used to explore the influence of nozzle geometry and length on the temporal evolution of flow and reaction processes, engine performance parameters, and noise generation.

Xing He; Ann Karagozian

2003-01-01

201

Experimental Study of a Pulse Detonation Engine Driven Ejector  

NASA Technical Reports Server (NTRS)

Results of an experimental effort on pulse detonation driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE)/ejector setup that was specifically designed for the study. The results of various experiments designed to probe different aspects of the PDE/ejector setup are reported. The baseline PDE was operated using ethylene (C2H4) as the fuel and an oxygen/nitrogen (O2 + N2) mixture at an equivalence ratio of one. The PDE only experiments included propellant mixture characterization using a laser absorption technique, high fidelity thrust measurements using an integrated spring-damper system, and shadowgraph imaging of the detonation/shock wave structure emanating from the tube. The baseline PDE thrust measurement results are in excellent agreement with experimental and modeling results reported in the literature. These PDE setup results were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups with constant diameter ejector tubes and various detonation tube/ejector tube overlap distances. The results show that for the geometries studied here, a maximum thrust augmentation of 24% is achieved. Further increases are possible by tailoring the ejector geometry based on CFD predictions conducted elsewhere. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

Santoro, Robert J.; Pal, Sibtosh; Shehadeh, R.; Saretto, S.; Lee, S.-Y.

2005-01-01

202

ASYMMETRY AND THE NUCLEOSYNTHETIC SIGNATURE OF NEARLY EDGE-LIT DETONATION IN WHITE DWARF CORES  

SciTech Connect

Most of the leading explosion scenarios for Type Ia supernovae involve the nuclear incineration of a white dwarf star through a detonation wave. Several scenarios have been proposed as to how this detonation may actually occur, but the exact mechanism and environment in which it takes place remain unknown. We explore the effects of an off-center initiated detonation on the spatial distribution of the nucleosynthetic yield products in a toy model-a pre-expanded near Chandrasekhar-mass white dwarf. We find that a single-point near edge-lit detonation results in asymmetries in the density and thermal profiles, notably the expansion timescale, throughout the supernova ejecta. We demonstrate that this asymmetry of the thermodynamic trajectories should be common to off-center detonations where a small amount of the star is burned prior to detonation. The sensitivity of the yields on the expansion timescale results in an asymmetric distribution of the elements synthesized as reaction products. We tabulate the shift in the center of mass of the various elements produced in our model supernova and find an odd-even pattern for elements past silicon. Our calculations show that off-center single-point detonations in carbon-oxygen white dwarfs are marked by significant composition asymmetries in their remnants which bear potentially observable signatures in both velocity and coordinate space, including an elemental nickel mass fraction that varies by a factor of 2-3 from one side of the remnant to the other.

Chamulak, David A.; Truran, James W. [Argonne National Laboratory, Argonne, IL (United States); Meakin, Casey A. [Steward Observatory, University of Arizona, Tucson, AZ (United States); Seitenzahl, Ivo R., E-mail: dchamulak@anl.gov [Max Planck Institute for Astrophysics, Garching (Germany)

2012-01-01

203

Airbreathing Pulse Detonation Engine Performance  

NASA Technical Reports Server (NTRS)

This paper presents performance results for pulse detonation engines taking into account the effects of dissociation and recombination. The amount of sensible heat recovered through recombination in the PDE chamber and exhaust process was found to be significant. These results have an impact on the specific thrust, impulse and fuel consumption of the PDE.

Povinelli, Louis A.; Yungster, Shaye

2002-01-01

204

Sensitized Liquid Hydrazine Detonation Studies  

NASA Technical Reports Server (NTRS)

Vapor-phase hydrazine (N2H4) is known to be very sensitive to detonation while liquid hydrazine is very insensitive to detonation, theoretically requiring extremely high pressures to induce initiation. A review of literature on solid and liquid explosives shows that when pure explosive substances are infiltrated with gas cavities, voids, and/or different phase contaminants, the energy or shock pressure necessary to induce detonation can decrease by an order of magnitude. Tests were conducted with liquid hydrazine in a modified card-gap configuration. Sensitization was attempted by bubbling helium gas through and/or suspending ceramic microspheres in the liquid. The hydrazine was subjected to the shock pressure from a 2 lb (0.9 kg) Composition C-4 explosive charge. The hydrazine was contained in a 4 in. (10.2 cm) diameter stainless steel cylinder with a 122 in(sup 3) (2 L) volume and sealed with a polyethylene cap. Blast pressures from the events were recorded by 63 high speed pressure transducers located on three radial legs extending from 4 to 115 ft (1.2 to 35.1 in) from ground zero. Comparison of the neat hydrazine and water baseline tests with the "sensitized" hydrazine tests indicates the liquid hydrazine did not detonate under these conditions.

Rathgeber, K. A.; Keddy, C. P.; Bunker, R. L.

1999-01-01

205

MULTI-DIMENSIONAL MODELS FOR DOUBLE DETONATION IN SUB-CHANDRASEKHAR MASS WHITE DWARFS  

SciTech Connect

Using two-dimensional and three-dimensional simulations, we study the ''robustness'' of the double detonation scenario for Type Ia supernovae, in which a detonation in the helium shell of a carbon-oxygen white dwarf induces a secondary detonation in the underlying core. We find that a helium detonation cannot easily descend into the core unless it commences (artificially) well above the hottest layer calculated for the helium shell in current presupernova models. Compressional waves induced by the sliding helium detonation, however, robustly generate hot spots which trigger a detonation in the core. Our simulations show that this is true even for non-axisymmetric initial conditions. If the helium is ignited at multiple points, then the internal waves can pass through one another or be reflected, but this added complexity does not defeat the generation of the hot spot. The ignition of very low-mass helium shells depends on whether a thermonuclear runaway can simultaneously commence in a sufficiently large region.

Moll, R.; Woosley, S. E. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2013-09-10

206

Development of a Gas-Fed Pulse Detonation Research Engine  

NASA Technical Reports Server (NTRS)

In response to the growing need for empirical data on pulse detonation engine performance and operation, NASA Marshall Space Flight Center has developed and placed into operation a low-cost gas-fed pulse detonation research engine. The guiding design strategy was to achieve a simple and flexible research apparatus, which was inexpensive to build and operate. As such, the engine was designed to operate as a heat sink device, and testing was limited to burst-mode operation with run durations of a few seconds. Wherever possible, maximum use was made of standard off-the-shelf industrial or automotive components. The 5-cm diameter primary tube is about 90-cm long and has been outfitted with a multitude of sensor and optical ports. The primary tube is fed by a coaxial injector through an initiator tube, which is inserted directly into the injector head face. Four auxiliary coaxial injectors are also integrated into the injector head assembly. All propellant flow is controlled with industrial solenoid valves. An automotive electronic ignition system was adapted for use, and spark plugs are mounted in both tubes so that a variety of ignition schemes can be examined. A microprocessor-based fiber-optic engine control system was developed to provide precise control over valve and ignition timing. Initial shakedown testing with hydrogen/oxygen mixtures verified the need for Schelkin spirals in both the initiator and primary tubes to ensure rapid development of the detonation wave. Measured pressure wave time-of-flight indicated detonation velocities of 2.4 km/sec and 2.2 km/sec in the initiator and primary tubes, respectively. These values implied a fuel-lean mixture corresponding to an H2 volume fraction near 0.5. The axial distribution for the detonation velocity was found to be essentially constant along the primary tube. Time-resolved thrust profiles were also acquired for both underfilled and overfilled tube conditions. These profiles are consistent with previous time-resolved measurements on single-cycle tubes where the thrust is found to peak as the detonation wave exits the tube, and decay as the tube blows down.

Litchford, Ron J.; Hutt, John (Technical Monitor)

2001-01-01

207

Fluid dynamics in a Rotating-Detonation-Engine with micro-injectors  

NASA Astrophysics Data System (ADS)

Rotating detonation engines (RDE's) represent a natural extension of the extensively studied pulse detonation engines (PDE's) for obtaining propulsion from the high efficiency detonation cycle. RDE's require fuel and oxidizer under high pressure to be injected through micro-nozzles from one or two plenums (for premixed and non-premixed). This injection process is critically important to the stability and performance of the RDE. This paper studies the effect of this injection process on the detonation wave within the combustion chamber, with an emphasis on how the fluid dynamics are affected. Both two-dimensional and three-dimensional simulations are done using well proven numerical methods for both the combustion chamber and mixture plenums of an idealized RDE.

Schwer, Douglas

2011-11-01

208

THE EFFECT OF THE PRE-DETONATION STELLAR INTERNAL VELOCITY PROFILE ON THE NUCLEOSYNTHETIC YIELDS IN TYPE Ia SUPERNOVA  

SciTech Connect

A common model of the explosion mechanism of Type Ia supernovae is based on a delayed detonation of a white dwarf. A variety of models differ primarily in the method by which the deflagration leads to a detonation. A common feature of the models, however, is that all of them involve the propagation of the detonation through a white dwarf that is either expanding or contracting, where the stellar internal velocity profile depends on both time and space. In this work, we investigate the effects of the pre-detonation stellar internal velocity profile and the post-detonation velocity of expansion on the production of {alpha}-particle nuclei, including {sup 56}Ni, which are the primary nuclei produced by the detonation wave. We perform one-dimensional hydrodynamic simulations of the explosion phase of the white dwarf for center and off-center detonations with five different stellar velocity profiles at the onset of the detonation. In order to follow the complex flows and to calculate the nucleosynthetic yields, approximately 10,000 tracer particles were added to every simulation. We observe two distinct post-detonation expansion phases: rarefaction and bulk expansion. Almost all the burning to {sup 56}Ni occurs only in the rarefaction phase, and its expansion timescale is influenced by pre-existing flow structure in the star, in particular by the pre-detonation stellar velocity profile. We find that the mass fractions of the {alpha}-particle nuclei, including {sup 56}Ni, are tight functions of the empirical physical parameter {rho}{sub up}/v{sub down}, where {rho}{sub up} is the mass density immediately upstream of the detonation wave front and v{sub down} is the velocity of the flow immediately downstream of the detonation wave front. We also find that v{sub down} depends on the pre-detonation flow velocity. We conclude that the properties of the pre-existing flow, in particular the internal stellar velocity profile, influence the final isotopic composition of burned matter produced by the detonation.

Kim, Yeunjin; Jordan, G. C. IV; Graziani, Carlo; Lamb, D. Q.; Truran, J. W. [Astronomy Department, University of Chicago, Chicago, IL 60637 (United States); Meyer, B. S. [Physics and Astronomy Department, Clemson University, Clemson, SC 29634 (United States)

2013-07-01

209

Cellular pattern evolution in gaseous detonation diffraction in a 90-degree-branched channel  

SciTech Connect

This paper presents recent results of an experimental investigation on gaseous detonation diffraction in a 90-degree-branched channel. The entire process of diffraction is demonstrated by cellular patterns and the analysis is mainly based on their evolution. Detonation pressure history and velocity are measured and the corresponding cellular patterns are recorded on soot foils around the branched segment. Results show that detonation propagation is notably disturbed by the branched wall geometry and that a complex wave configuration appears in both channels. Cellular patterns show that an expansion fan appears at the T-junction area with a Mach reflection taking place in the horizontal channel, while regular reflection takes place in the vertical channel. Subsequently, it appears that there is a transition from a regular reflection to a Mach reflection in the vertical channel. Details of the cellular pattern indicate that from the early stage to the end of diffraction, the detonation wave sequentially experiences attenuation, front decoupling, and degradation into deflagration, reinitiation, and recuperation. According to cellular pattern evolution and velocity measurement, a recuperated detonation with nearly the same velocity as the undisturbed incoming wave finally develops downstream in both channels, at a distance of about four times the channel height (160 mm). The mechanism of diffraction is explored based on the ZND (Zel'dovich-von Neumann-Doering) model, and the soot foils in both channels show a pattern consistent with air shock-wave diffraction in a 90-degree-branched channel. (author)

Guo, Changming; Wang, Changjian; Xu, Shengli [Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100080 (China); Zhang, Hanhong [Department of Mechanics and Mechanical Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2007-02-15

210

Numerical study of detonation transmission in mixtures containing chemical inhibitors  

NASA Astrophysics Data System (ADS)

In this article, we report on numerical simulations of the evolution of gaseous detonation waves in mixtures that contain chemical inhibitors. In general, these are compounds that consume the radicals that are produced during combustion, thereby inhibiting the exothermic chain-terminating reaction. Also, some of them participate in endothermic reactions, such as dissociation. These properties make them very efficient flame suppressants. In this study, we employ a chemical kinetics model that consists of a three-step chain-branching mechanism for the fuel combustion and a one-step mechanism for the reaction between inhibitor and radicals. Results from both one- and two-dimensional simulations are presented and discussed. It is shown that radical consumption and heat absorption due to the inhibitor's reaction result in longer induction zones. This, in turn, leads to a detachment of the reaction zone from the precursor shock. For small and medium inhibitor concentrations, this detachment is temporary. Eventually, the radical concentration behind the induction zone becomes sufficient to initiate rapid fuel consumption, thus producing pressure waves which reach the precursor shock and re-ignite the detonation. This is followed by large over-pressures and highly irregular oscillations of the shock. Nonetheless, sufficiently high inhibitor concentrations can yield permanent detonation quenching.

Papalexandris, M. V.

2012-05-01

211

Ignition and detonation of solid explosives: a micromechanical burn model  

NASA Astrophysics Data System (ADS)

This paper describes a new computational framework for modeling splid explosives and proof-of-concept calculations. Our goal is to expand predictive model capability through the inclusion of various micro-mechanical burn processes. We propose a model which is complicated enough to represent underlying physics, but simple enough for engineering scale computations. Key components of the model include energy localization, the growth of hot spots, micro-mechanics in/around hot spots, and a phase-averaged mixture equation of state. The nucleation and growth of locally heated regions is treated by a statistical model based on an exponential size distribution. Proof-of-concept calculations are limited to shock loading, but show the capability of simulating Pop-plots, initial temperature effect, detonation waves in 2D, detonation shock confinement test, and multi-dimensional effects in a unified fashion based on micro-physics.

Hamate, Y.; Horie, Y.

2006-12-01

212

Non-detonable explosive simulators  

DOEpatents

A simulator which is chemically equivalent to an explosive, but is not detonable. The simulator has particular use in the training of explosives detecting dogs and calibrating sensitive analytical instruments. The explosive simulants may be fabricated by different techniques, a first involves the use of standard slurry coatings to produce a material with a very high binder to explosive ratio without masking the explosive vapor, and the second involves coating inert beads with thin layers of explosive molecules.

Simpson, Randall L. (Livermore, CA); Pruneda, Cesar O. (Livermore, CA)

1994-01-01

213

Phase detonated shock tube (PFST)  

NASA Astrophysics Data System (ADS)

Mesa2D hydrocode has been used to model the collapse of 304SS cylinder onto the 6061Al phasing lens, shock in the lines, phase detonation of the PBX 9501 explosive, and Mach disk position. The phase velocity in the system was meausred in microwave-interferometry experiments, and favorably compared with the calculations. The technique allows to accelerate a thin plate intact to above 1 cm/micro-s. (AIP)

Zerwekh, W. D.; Marsh, S. P.; Tan, T.-H.

1994-07-01

214

Non-detonable explosive simulators  

DOEpatents

A simulator which is chemically equivalent to an explosive, but is not detonable. The simulator has particular use in the training of explosives detecting dogs and calibrating sensitive analytical instruments. The explosive simulants may be fabricated by different techniques, a first involves the use of standard slurry coatings to produce a material with a very high binder to explosive ratio without masking the explosive vapor, and the second involves coating inert beads with thin layers of explosive molecules. 5 figs.

Simpson, R.L.; Pruneda, C.O.

1994-11-01

215

Unconfined aluminum particles-air detonation  

Microsoft Academic Search

The detonability of aluminum (Al) particles suspended in air is an important fundamental problem in understanding the limits\\u000a of multiphase explosion in a metal particles-gas flow. Al particles possess an oxide coating that has a high melting temperature,\\u000a thus further increasing the difficulty in understanding their detonation mechanism. Micrometric Al-air detonation at atmospheric\\u000a conditions is feasible in large tubes 0.12-0.3

F. Zhang; K. B. Gerrard; R. C. Ripley; V. Tanguay

216

Improved detonation modeling with CHEETAH  

SciTech Connect

A Livermore software program called CHEETAH, an important, even indispensable tool for energetic materials researchers worldwide, was made more powerful in the summer of 1997 with the release of CHEETAH 2.0, an advanced version that simulates a wider variety of detonations. Derived from more than 40 years of experiments on high explosives at Lawrence Livermore and Los Alamos national laboratories, CHEETAH predicts the results from detonating a mixture of specified reactants. It operates by solving thermodynamic equations to predict detonation products and such properties as temperature, pressure, volume, and total energy released. The code is prized by synthesis chemists and other researchers because it allows them to vary the starting molecules and conditions to optimize the desired performance properties. One of the Laboratory`s most popular computer codes, CHEETAH is used at more than 200 sites worldwide, including ones in England, Canada, Sweden, Switzerland, and France. Most sites are defense-related, although a few users, such as Japanese fireworks researchers, are in the civilian sector.

Heller, A.

1997-11-01

217

Curved detonation fronts in solid explosives 1 Curved detonation fronts in solid explosives  

E-print Network

Curved detonation fronts in solid explosives 1 Curved detonation fronts in solid explosives(). At the edges of the explosive, Dn() is supplemented with boundary conditons. By direct numerical simulation for simulating complex explosive-containing systems. Key words: Detonation, Curvature eect, Edge interactions

Aslam, Tariq

218

Non-Equilibrium Zeldovich-Von Neumann-Doring Theory and Reactive Flow Modeling of Detonation  

SciTech Connect

This paper discusses the Non-Equilibrium Zeldovich - von Neumann - Doring (NEZND) theory of self-sustaining detonation waves and the Ignition and Growth reactive flow model of shock initiation and detonation wave propagation in solid explosives. The NEZND theory identified the non-equilibrium excitation processes that precede and follow the exothermic decomposition of a large high explosive molecule into several small reaction product molecules. The thermal energy deposited by the leading shock wave must be distributed to the vibrational modes of the explosive molecule before chemical reactions can occur. The induction time for the onset of the initial endothermic reactions can be calculated using high pressure, high temperature transition state theory. Since the chemical energy is released well behind the leading shock front of a detonation wave, a physical mechanism is required for this chemical energy to reinforce the leading shock front and maintain its overall constant velocity. This mechanism is the amplification of pressure wavelets in the reaction zone by the process of de-excitation of the initially highly vibrationally excited reaction product molecules. This process leads to the development of the three-dimensional structure of detonation waves observed for all explosives. For practical predictions of shock initiation and detonation in hydrodynamic codes, phenomenological reactive flow models have been developed. The Ignition and Growth reactive flow model of shock initiation and detonation in solid explosives has been very successful in describing the overall flow measured by embedded gauges and laser interferometry. This reactive flow model uses pressure and compression dependent reaction rates, because time resolved experimental temperature data is not yet available. Since all chemical reaction rates are ultimately controlled by temperature, the next generation of reactive flow models will use temperature dependent reaction rates. Progress on a statistical hot spot ignition and growth reactive flow model with multistep Arrhenius chemical reaction pathways is discussed.

Tarver, C M; Forbes, J W; Urtiew, P A

2002-05-02

219

Examination of the Various Cycles for Pulse Detonation Engines  

E-print Network

Examination of the Various Cycles for Pulse Detonation Engines R. Vutthivithayarak, Eric M. Braun and the need for precompression are addressed. I. Introduction Airbreathing pulse detonation engines (PDEs

Texas at Arlington, University of

220

Mechanism of deflagration-to-detonation transitions above repeated obstacles  

NASA Astrophysics Data System (ADS)

Experiments are carried out to investigate the mechanism of the deflagration-to-detonation transition (DDT). Because, this mechanism has relevance to safety issues in industries, where combustible premixed gases are in general use. A stoichiometric gas of oxygen and hydrogen (oxy-hydrogen) is ignited in a tube, repeated obstacles are installed, and the DDT behaviours are visualized using a high-speed video camera. The pitch and height of the repeated obstacles and the initial pressure of the oxy-hydrogen premixed gas are varied in an attempt to obtain the optimum conditions that cause DDT a short distance from the ignition source. The experiments identified DDT as being essentially caused by one of the following mechanisms: (1) A deflagration wave is accelerated in terms of a vortex, which is generated behind the obstacle, and the flame acceleration induces a secondary shock wave. Eventually, the shock-flame interaction ahead of the obstacle causes DDT via a very strong local explosion. (2) Each shock wave generated by relatively weak local explosions between the obstacles is not sufficient to cause DDT directly, but DDT results from an accumulation of shock waves. The detonation induction distance is also examined, taking into account the physical and chemical parameters of the obstacles and the oxy-hydrogen premixed gas.

Obara, T.; Kobayashi, T.; Ohyagi, S.

2012-11-01

221

Detonation in tungsten-loaded HMX  

SciTech Connect

The detonation behavior of X-0233, a heavily tungsten-loaded HMX explosive, has been studied using failure diameter measurements, plate dents, and aquarium tests. A model with features resembling those of a weak detonation describe the experimental results. 7 refs., 10 figs.

Goldstein, S.; Mader, C.L.

1985-01-01

222

Detonation Shock Dynamics Calibration of PBX 9501  

NASA Astrophysics Data System (ADS)

Detonation Shock Dynamics (DSD) has proven to be a fast and accurate alternative to direct numerical simulation of propagating detonations. Here, the requisite differential equations, experimental data and calibration procedure will be outlined for the plastic bonded explosive PBX 9501. It will be shown that the DSD model can fit the existing PBX 9501 data to within the experimental uncertainty.

Aslam, Tariq D.

2007-12-01

223

Detonation Structure Simulation with AMROC Ralf Deiterding  

E-print Network

simulations can be the key to the thorough under- standing of the multi-dimensional nature of transient in purely Cartesian geometry and a two- dimensional detonation propagating through a smooth 60 degree pipe the one-dimensional detonation struc- ture correctly, but experiments [21] uncovered that the reduction

Barr, Al

224

FLOW TEST FOR PULSE DETONATION ENGINE  

Microsoft Academic Search

A test was conducted to measure the time-averaged flow rate of a pulse detonation engine. The objective of this flow test was to determine the flow effectiveness of a pulse detonation engine utilizing a rotating spool of tubes. Since thrust is directly proportional to flow, the ability of the device to pass flow at operating rotational speeds is critical to

Eric J. Gamble; Jose Gutierrez; Evan Riordan

225

Pulse detonation assembly and hybrid engine  

NASA Technical Reports Server (NTRS)

A pulse detonation (PD) assembly includes a number of PD chambers adapted to expel respective detonation product streams and a number of barriers disposed between respective pairs of PD chambers. The barriers define, at least in part, a number of sectors that contain at least one PD chamber. A hybrid engine includes a number of PD chambers and barriers. The hybrid engine further includes a turbine assembly having at least one turbine stage, being in flow communication with the PD chambers and being configured to be at least partially driven by the detonation product streams. A segmented hybrid engine includes a number of PD chambers and segments configured to receive and direct the detonation product streams from respective PD chambers. The segmented hybrid engine further includes a turbine assembly configured to be at least partially driven by the detonation product streams.

Rasheed, Adam (Inventor); Dean, Anthony John (Inventor); Vandervort, Christian Lee (Inventor)

2010-01-01

226

Performance characterization of the NASA standard detonator  

SciTech Connect

The NASA Standard Detonator (NSD) is employed in support of a number of current applications, including the Space Shuttle. This effort was directed towards providing test results to characterize the output of this device for its use in a safe and arm device. As part of the investigation, flash X-ray was used to provide stop-motion photographs of the flying metal plate that is created by initiation of the detonator. This provided researchers with a better understanding of the shape and character of the high-velocity disk as it propagated across the gap between the detonator and next assembly. The second portion of the study used a velocity interferometer to evaluate the acceleration and velocity histories of the flying plate, providing a quantified assessment of the detonator`s ability to initiate the explosive in the next explosive.

Tarbell, W.W. [Sandia National Labs., Albuquerque, NM (United States); Burke, T.L.; Solomon, S.E. [Component Engineering, USBI, Huntsville, AL (United States)

1995-05-01

227

Tritium labeling of detonation nanodiamonds.  

PubMed

For the first time, the radioactive labeling of detonation nanodiamonds was efficiently achieved using a tritium microwave plasma. According to our measurements, the total radioactivity reaches 9120 ± 120 ?Ci mg(-1), with 93% of (3)H atoms tightly bonded to the surface and up to 7% embedded into the diamond core. Such (3)H doping will ensure highly stable radiolabeled nanodiamonds, on which surface functionalization is still allowed. This breakthrough opens the way to biodistribution and pharmacokinetics studies of nanodiamonds, while this approach can be scalable to easily treat bulk quantities of nanodiamonds at low cost. PMID:24492594

Girard, Hugues A; El-Kharbachi, Abdelouahab; Garcia-Argote, Sébastien; Petit, Tristan; Bergonzo, Philippe; Rousseau, Bernard; Arnault, Jean-Charles

2014-03-18

228

On the Exit Boundary Condition for One-Dimensional Calculations of Pulsed Detonation Engine Performance  

NASA Technical Reports Server (NTRS)

In one-dimensional calculations of pulsed detonation engine (PDE) performance, the exit boundary condition is frequently taken to be a constant static pressure. In reality, for an isolated detonation tube, after the detonation wave arrives at the exit plane, there will be a region of high pressure, which will gradually return to ambient pressure as an almost spherical shock wave expands away from the exit, and weakens. Initially, the flow is supersonic, unaffected by external pressure, but later becomes subsonic. Previous authors have accounted for this situation either by assuming the subsonic pressure decay to be a relaxation phenomenon, or by running a two-dimensional calculation first, including a domain external to the detonation tube, and using the resulting exit pressure temporal distribution as the boundary condition for one-dimensional calculations. These calculations show that the increased pressure does affect the PDE performance. In the present work, a simple model of the exit process is used to estimate the pressure decay time. The planar shock wave emerging from the tube is assumed to transform into a spherical shock wave. The initial strength of the spherical shock wave is determined from comparison with experimental results. Its subsequent propagation, and resulting pressure at the tube exit, is given by a numerical blast wave calculation. The model agrees reasonably well with other, limited, results. Finally, the model was used as the exit boundary condition for a one-dimensional calculation of PDE performance to obtain the thrust wall pressure for a hydrogen-air detonation in tubes of length to diameter ratio (L/D) of 4, and 10, as well as for the original, constant pressure boundary condition. The modified boundary condition had no performance impact for values of L/D > 10, and moderate impact for L/D = 4.

Wilson, Jack; Paxson, Daniel E.

2002-01-01

229

Use of limits of initiation of liquid explosives for determining detonation pressures  

Microsoft Academic Search

In this report, a modification of the method of reflection for the measurement of dynamic pressures is described in which data are used concerning the limits of detonation initiation of liquid explosives by shock waves. It is very simple technically, does not require the use of unique and complex apparatus, and ensures a high measurement accuracy. The possibilities of the

I. M. Voskoboinikov; N. F. Voskoboinikova

1977-01-01

230

Molecular Dynamics Simulations of Weak Detonations Morag Am-Shallem,1  

E-print Network

of a stable fast reactive shock wave. The terminal shock velocity is independent of the initiation conditions behind the shock front. The dependence of the shock velocity on crystal nonlinear compressibility in detonation velocity with the reaction exothermicity reaching a saturation value is observed. In all other

Kosloff, Ronnie

231

Pulse detonation propulsion: challenges, current status, and future perspective  

Microsoft Academic Search

The paper is focused on recent accomplishments in basic and applied research on pulse detonation engines (PDE) and various PDE design concepts. Current understanding of gas and sprary detonations, thermodynamic grounds for detonation-based propulsion, principles of practical implementation of the detonation-based thermodynamic cycle, and various operational constraints of PDEs are discussed.

G. D. Roy; S. M. Frolov; A. A. Borisov; D. W. Netzer

2004-01-01

232

Response of critical tube diameter phenomenon to small perturbations for gaseous detonations  

NASA Astrophysics Data System (ADS)

In this experimental study, the critical tube diameter phenomenon of gaseous detonations is investigated in both stable and unstable mixtures with focus on the failure mechanism. It was previously postulated that in unstable mixtures, where the cellular detonation front is highly irregular, the failure is caused by the suppression of local re-initiation centers linked to the dynamics of instabilities. In stable mixtures, typically with high argon dilution, the detonation structure is very regular and the failure mode is attributed to the excessive curvature of the global front. In order to differentiate between these two failure mechanisms, flow perturbations are introduced by placing an obstacle resulting in a minimal blockage ratio of approximately 8 %. The obstacle is placed at the tube exit, before the detonation diffraction. Results show that the perturbations caused by the obstacle only have an effect on undiluted (i.e., unstable) mixtures, causing a decrease in the minimum initial pressure required for successful detonation transmission. This thus demonstrates that local hydrodynamic instabilities play an important role for the critical tube diameter phenomenon in undiluted, unstable mixtures. In contrast, the results for the stable, argon-diluted mixture exhibit little variation in critical initial pressure between the perturbed and unperturbed cases. This can be attributed to the minimal effect of the perturbations on global curvature for the emergent detonation wave. The geometry of the perturbation is also tested, while holding the blockage area constant, by varying the number and position of the obstacle(s). The results demonstrate that the transmission of a detonation is independent of the blockage geometry and is only a function of its imposed blockage area. Consequently, the change in required minimum pressure for transmission shows an identical behavior in unstable mixtures for different perturbation geometries while the transmission characteristics of the stable mixture remain unaffected.

Mehrjoo, N.; Zhang, B.; Portaro, R.; Ng, H. D.; Lee, J. H. S.

2014-03-01

233

Experimental Study of Propane-Fueled Pulsed Detonation Rocket  

Microsoft Academic Search

A major problem applying detonations into aero-propulsive devices is the transition of deflagration and weak deto- nation into CJ detonation. The longer this transition, the longer the physical length of the engine must be to facilitate the propagation of the flame. However, lengthening of the detonation chamber can significantly increase weight, rendering the reduction of deflagration-to-detonation (DDT) and weak detonation

Frank K. Lu; Jason M. Meyers; Donald R. Wilson

234

Detonator comprising a nonlinear transmission line  

DOEpatents

Detonators are described herein. In a general embodiment, the detonator includes a nonlinear transmission line that has a variable capacitance. Capacitance of the nonlinear transmission line is a function of voltage on the nonlinear transmission line. The nonlinear transmission line receives a voltage pulse from a voltage source and compresses the voltage pulse to generate a trigger signal. Compressing the voltage pulse includes increasing amplitude of the voltage pulse and decreasing length of the voltage pulse in time. An igniter receives the trigger signal and detonates an explosive responsive to receipt of the trigger signal.

Elizondo-Decanini, Juan M

2014-12-30

235

Eigenvalue Detonation of Combined Effects Aluminized Explosives  

NASA Astrophysics Data System (ADS)

Theory and performance for recently developed combined—effects aluminized explosives are presented. Our recently developed combined-effects aluminized explosives (PAX-29C, PAX-30, PAX-42) are capable of achieving excellent metal pushing, as well as high blast energies. Metal pushing capability refers to the early volume expansion work produced during the first few volume expansions associated with cylinder and wall velocities and Gurney energies. Eigenvalue detonation explains the observed detonation states achieved by these combined effects explosives. Cylinder expansion data and thermochemical calculations (JAGUAR and CHEETAH) verify the eigenvalue detonation behavior.

Capellos, C.; Baker, E. L.; Nicolich, S.; Balas, W.; Pincay, J.; Stiel, L. I.

2007-12-01

236

Effect of compressibility of additive on rate of detonation of mixed charges  

SciTech Connect

Results of a series of tests for charges of TNT, octogen, and hexogen, containing as additives the chlorides of sodium and potassium, boron nitride, aluminum talc, benzene, hexane, and solutions of carbon tetrachloride and hexane with the same density as benzene were evaluated. Three series of tests were conducted to determine detonation speed and the effect of the additive compressibility on detonation speed and on the speed determination accuracy. The results showed that polymorphic or other transformations under impact wave compression resulting in a significant change in the specific volume of the additive cause a further reduction in the speed of detonation, greater than the normal experimental error. A study of the effect of introducing an additive into the charge can be used to provide information on the compressibility of the additive and the possibility of transformations, with a significant change in the specific volume, occurring under pressure conditions.

Voskoboinikov, I.M.; Gogulya, M.F.; Dimza, G.V.

1988-05-01

237

Investigations on deflagration to detonation transition in porous energetic materials. Final report  

SciTech Connect

The research carried out by this contract was part of a larger effort funded by LANL in the areas of deflagration to detonation in porous energetic materials (DDT) and detonation shock dynamics in high explosives (DSD). In the first three years of the contract the major focus was on DDT. However, some researchers were carried out on DSD theory and numerical implementation. In the last two years the principal focus of the contract was on DSD theory and numerical implementation. However, during the second period some work was also carried out on DDT. The paper discusses DDT modeling and DSD modeling. Abstracts are included on the following topics: modeling deflagration to detonation; DSD theory; DSD wave front tracking; and DSD program burn implementation.

Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States)

1999-07-01

238

CHARACTERIZING DETONATING LX-17 CHARGES CROSSING A TRANSVERSE AIR GAP WITH EXPERIMENTS AND MODELING  

SciTech Connect

Experiments were performed using detonating LX-17 (92.5% TATB, 7.5% Kel-F by weight) charges with various width transverse air gaps with manganin peizoresistive in-situ gauges present. The experiments, performed with 25 mm diameter by 25 mm long LX-17 pellets with the transverse air gap in between, showed that transverse gaps up to about 3 mm could be present without causing the detonation wave to fail to continue as a detonation. The Tarantula/JWL{sup ++} code was utilized to model the results and compare with the in-situ gauge records with some agreement to the experimental data with additional work needed for a better match to the data. This work will present the experimental details as well as comparison to the model results.

Lauderbach, L M; Souers, P C; Garcia, F; Vitello, P; Vandersall, K S

2009-06-26

239

Waves  

NSDL National Science Digital Library

We will review some basic properties of waves and then further explore sound and light. For a quick overview of some properties of all waves, click on this first site. Make sure you fill out your hand out as you work! Waves and Wave Motion : Describing Waves Practice what you've already learned about waves with this site: Waves This site will let you play around some more with transverse waves: Wave on a String Sound waves are mechanical waves, ...

Petersen, Mrs.

2014-05-27

240

Propagation of detonations in hydrazine vapor  

NASA Technical Reports Server (NTRS)

In the range of greater hydrazine vapor pressure, detonation speed depends exclusively on the extent of the ammonia decomposition in the second reaction stage. As vapor pressure decreases, the ammonia disintegration speed becomes increasingly slower and the reaction reached in the reaction zone increasingly decreases until finally, in the vapor pressure range between 53 and 16 Torr, the contribution of the second stage to detonation propagation disappears, and only the first stage remains active. Since the disintegration speed of the hydrazine in this pressure range has decreased markedly as well, no level, but rather only spinning, detonations occur. Temporary separations of the impact front and the reaction zone in the process lead to fluctuations of the detonation speed.

Heinrich, H. J.

1985-01-01

241

Supporting Structure of the LSD Wave in an Energy Absorption Perspective  

SciTech Connect

In Repetitively Pulsed (RP) Laser Propulsion, laser energy irradiated to a vehicle is converted to blast wave enthalpy during the Laser Supported Detonation (LSD) regime. Based on the measured post-LSD electron number density profiles by two-wavelength Mach Zehnder interferometer in a line-focusing optics, electron temperature and absorption coefficient were estimated assuming Local Thermal Equilibrium. A 10J/pulse CO{sub 2} laser was used. As a result, laser absorption was found completed in the layer between the shock wave and the electron density peak. Although the LSD-termination timing was not clear from the shock-front/ionization-front separation in the shadowgraph images, there observed drastic changes in the absorption layer thickness from 0.2 mm to 0.5 mm and in the peak heating rate from 12-17x10{sup 13} kW/m{sup 3} to 5x10{sup 13} kW/m{sup 3} at the termination.

Fukui, Akihiro; Hatai, Keigo; Cho, Shinatora; Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, School of Engineering, University of Tokyo (Japan); Komurasaki, Kimiya [Department of Advanced Energy, School of Frontier Sciences, University of Tokyo (Japan)

2008-04-28

242

A flash vaporization system for detonation of hydrocarbon fuels in a pulse detonation engine  

Microsoft Academic Search

Current research by both the US Air Force and Navy is concentrating on obtaining detonations in a pulse detonation engine (PDE) with low vapor pressure, kerosene based jet fuels. These fuels, however, have a low vapor pressure and the performance of a liquid hydrocarbon fueled PDE is significantly hindered by the presence of fuel droplets. A high pressure, fuel flash

Kelly Colin Tucker

2005-01-01

243

Desensitization of pressed RDX/paraffin and HMX/paraffin compounds by multiple shock waves  

SciTech Connect

Multiple shock initiation of detonation in pressed RDX/paraffin and HMX/paraffin compounds is studied. If the explosive is preshocked by a weak shock wave, the effect of desensitization is observed, which is detectable by two features. First, a weak reaction appears behind the second shock wave. Second, the run to detonation increases by 100% for pressed RDX. Experiments with the samples of pressed RDX show that the run to detonation in preloaded explosive can be estimated from the distance at which the second wave overtakes the first weak shock; the run to detonation expected for the second shock wave, from Pop-plot data.

Bordzilovskii, S.A.; Karakhanov, S.M.

1995-09-01

244

Pulse Detonation Engine Air Induction System Analysis  

NASA Technical Reports Server (NTRS)

A preliminary mixed-compression inlet design concept for potential pulse-detonation engine (PDE) powered supersonic aircraft was defined and analyzed. The objectives of this research were to conceptually design and integrate an inlet/PDE propulsion system into a supersonic aircraft, perform time-dependent CFD analysis of the inlet flowfield, and to estimate the installed PDE cycle performance. The study was baselined to a NASA Mach 5 Waverider study vehicle in which the baseline over/under turboramjet engines were replaced with a single flowpath PDE propulsion system. As much commonality as possible was maintained with the baseline configuration, including the engine location and forebody lines. Modifications were made to the inlet system's external ramp angles and a rotating cowl lip was incorporated to improve off-design inlet operability and performance. Engines were sized to match the baseline vehicle study's ascent trajectory thrust requirement at Mach 1.2. The majority of this study was focused on a flight Mach number of 3.0. The time-dependent Navier Stokes CFD analyses of a two-dimensional approximation of the inlet was conducted for the Mach 3.0 condition. The Lockheed Martin Tactical Aircraft Systems-developed FALCON CFD code with a two equation 'k-1' turbulence model was used. The downstream PDE was simulated by an array of four sonic nozzles in which the flow areas were rapidly varied in various opening/closing combinations. Results of the CFD study indicated that the inlet design concept operated successfully at the Mach 3.0 condition, satisfying mass capture, total pressure recovery, and operability requirements. Time-dependent analysis indicated that pressure and expansion waves from the simulated valve perturbations did not effect the inlet's operability or performance.

Pegg, R. J.; Hunter, L. G.; Couch, B. D.

1996-01-01

245

Off-center ignition in type Ia supernova: I. Initial evolution and implications for delayed detonation  

E-print Network

The explosion of a carbon-oxygen white dwarf as a Type Ia supernova is known to be sensitive to the manner in which the burning is ignited. Studies of the pre-supernova evolution suggest asymmetric, off-center ignition, and here we explore its consequences in two- and three-dimensional simulations. Compared with centrally ignited models, one-sided ignitions initially burn less and release less energy. For the distributions of ignition points studied, ignition within two hemispheres typically leads to the unbinding of the white dwarf, while ignition within a small fraction of one hemisphere does not. We also examine the spreading of the blast over the surface of the white dwarf that occurs as the first plumes of burning erupt from the star. In particular, our studies test whether the collision of strong compressional waves can trigger a detonation on the far side of the star as has been suggested by Plewa et al. (2004). The maximum temperature reached in these collisions is sensitive to how much burning and expansion has already gone on, and to the dimensionality of the calculation. Though detonations are sometimes observed in 2D models, none ever happens in the corresponding 3D calculations. Collisions between the expansion fronts of multiple bubbles also seem, in the usual case, unable to ignite a detonation. "Gravitationally confined detonation" is therefore not a robust mechanism for the explosion. Detonation may still be possible in these models however, either following a pulsation or by spontaneous detonation if the turbulent energy is high enough.

F. K. Roepke; S. E. Woosley; W. Hillebrandt

2006-09-04

246

Off-Center Ignition in Type Ia Supernovae. I. Initial Evolution and Implications for Delayed Detonation  

NASA Astrophysics Data System (ADS)

The explosion of a carbon-oxygen white dwarf as a Type Ia supernova is known to be sensitive to the manner in which the burning is ignited. Studies of the presupernova evolution suggest asymmetric, off-center ignition, and here we explore its consequences in two- (2D) and three-dimensional (3D) simulations. Compared with centrally ignited models, one-sided ignitions initially burn less and release less energy. For the distributions of ignition points studied, ignition within two hemispheres typically leads to the unbinding of the white dwarf, while ignition within a small fraction of one hemisphere does not. We also examine the spreading of the blast over the surface of the white dwarf that occurs as the first plumes of burning erupt from the star. In particular, our studies test whether the collision of strong compressional waves can trigger a detonation on the far side of the star as has been suggested by Plewa and coworkers. The maximum temperature reached in these collisions is sensitive to how much burning and expansion has already gone on, and to the dimensionality of the calculation. Although detonations are sometimes observed in 2D models, none ever happens in the corresponding 3D calculations. Collisions between the expansion fronts of multiple bubbles also seem, in the usual case, unable to ignite a detonation. ``Gravitationally confined detonation'' is therefore not a robust mechanism for the explosion. Detonation may still be possible in these models, however, either following a pulsation or by spontaneous detonation if the turbulent energy is high enough.

Röpke, F. K.; Woosley, S. E.; Hillebrandt, W.

2007-05-01

247

Bactericidal effect of the Nd:YAG lasers in laser-supported curettage  

NASA Astrophysics Data System (ADS)

In this study, the efficacy of laser-supported curettage was examined with relation to the periodontitis-reference germs. Initially, a manual subgingival curettage followed by irradiation using the Nd:YAG-laser was carried out on 18 diseased periodontia. At two further appointments with weekly intervals, only laser irradiation was performed. Prior to and upon completion of therapy, subgingival plaque samples were taken at each appointment from all the treated periodontia. These were then examined microbiologically to establish the number of prevotella intermedia. A distinct bacterial reduction as well as a decrease in recolonization was shown. In conclusion the application of the Nd:YAG laser with a 400 micron fiber and an energy setting of 2 watts, 20 pps is beneficial when used in conjunction with manual periodontal treatment because of its disinfecting effect.

Gutknecht, Norbert; Fischer, Julia; Conrads, Georg; Lampert, Friedrich

1997-05-01

248

30 CFR 56.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2012 CFR

...MINES Explosives Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast...be deenergized. Such circuits need not be...

2012-07-01

249

30 CFR 57.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2011 CFR

...MINES Explosives Electric Blasting-Surface...6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the...deenergized. Such circuits need not be...

2011-07-01

250

30 CFR 57.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2012 CFR

...MINES Explosives Electric Blasting-Surface...6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the...deenergized. Such circuits need not be...

2012-07-01

251

30 CFR 56.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2014 CFR

...MINES Explosives Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast...be deenergized. Such circuits need not be...

2014-07-01

252

30 CFR 57.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2013 CFR

...MINES Explosives Electric Blasting-Surface...6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the...deenergized. Such circuits need not be...

2013-07-01

253

30 CFR 56.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2011 CFR

...MINES Explosives Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast...be deenergized. Such circuits need not be...

2011-07-01

254

30 CFR 57.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2014 CFR

...MINES Explosives Electric Blasting-Surface...6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the...deenergized. Such circuits need not be...

2014-07-01

255

30 CFR 56.6402 - Deenergized circuits near detonators.  

Code of Federal Regulations, 2013 CFR

...MINES Explosives Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast...be deenergized. Such circuits need not be...

2013-07-01

256

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2014 CFR

...false Compatibility of electric detonators. 57.6400 Section 57.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All...

2014-07-01

257

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2010 CFR

...false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...NONMETAL MINES Explosives Electric Blasting § 56.6400 Compatibility of electric detonators. All...

2010-07-01

258

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2014 CFR

...false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...NONMETAL MINES Explosives Electric Blasting § 56.6400 Compatibility of electric detonators. All...

2014-07-01

259

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2011 CFR

...false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...NONMETAL MINES Explosives Electric Blasting § 56.6400 Compatibility of electric detonators. All...

2011-07-01

260

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2011 CFR

...false Compatibility of electric detonators. 57.6400 Section 57.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All...

2011-07-01

261

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2013 CFR

...false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...NONMETAL MINES Explosives Electric Blasting § 56.6400 Compatibility of electric detonators. All...

2013-07-01

262

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2010 CFR

...false Compatibility of electric detonators. 57.6400 Section 57.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All...

2010-07-01

263

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2012 CFR

...false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...NONMETAL MINES Explosives Electric Blasting § 56.6400 Compatibility of electric detonators. All...

2012-07-01

264

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2012 CFR

...false Compatibility of electric detonators. 57.6400 Section 57.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All...

2012-07-01

265

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2013 CFR

...false Compatibility of electric detonators. 57.6400 Section 57.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All...

2013-07-01

266

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Transporting explosives and detonators. 75.1311 Section...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When...

2010-07-01

267

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Transporting explosives and detonators. 75.1311 Section...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When...

2012-07-01

268

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Transporting explosives and detonators. 75.1311 Section...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When...

2013-07-01

269

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2014 CFR

... 2014-07-01 false Transporting explosives and detonators. 75.1311 Section...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When...

2014-07-01

270

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Transporting explosives and detonators. 75.1311 Section...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When...

2011-07-01

271

Diameter Effect Curve and Detonation Front Curvature Measurements for ANFO  

NASA Astrophysics Data System (ADS)

Diameter effect and front curvature measurements are reported for rate stick experiments on commercially available prilled ANFO (ammonium nitrate-fuel oil) at ambient temperature. The shots were fired in paper tubes so as to provide minimal confinement. Diameters ranged from 77 mm. (? failure diameter) to 200 mm., with the tube length being ten diameters in all cases. Each detonation wave shape was fit with an analytic form, from which the local normal velocity Dn and total curvature ? were generated as a function of radius R, then plotted parametrically to generate a D_n(?) function. The resulting behavior deviates substantially from that of previous explosives,(Hill,L.G., Bdzil,J.B., and Aslam,T.D., 11^th) Detonation Symposium, 1998^,(Hill,L.G., Bdzil,J.B., Davis,W.C., and Engelke,R., Shock Compression of Condensed Matter, 1999) in which curves for different stick sizes overlay well for small ? but diverge for large ?, and for which ? increases monotonically with R to achieve a maximum value at the charge edge. For ANFO, we find that ? achieves a maximum at an intermediate R and that D_n(?) curves for different stick sizes are widely separated with no overlap whatsoever.

Catanach, R. A.; Hill, L. G.

2001-06-01

272

Thrust Augmentation Measurements for a Pulse Detonation Engine Driven Ejector  

NASA Technical Reports Server (NTRS)

Thrust augmentation results of an ongoing study of pulse detonation engine driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE) setup with various ejector configurations. The PDE used in these experiments utilizes ethylene (C2H4) as the fuel, and an equi-molar mixture of oxygen and nitrogen as the oxidizer at an equivalence ratio of one. High fidelity thrust measurements were made using an integrated spring damper system. The baseline thrust of the PDE engine was first measured and agrees with experimental and modeling results found in the literature. Thrust augmentation measurements were then made for constant diameter ejectors. The parameter space for the study included ejector length, PDE tube exit to ejector tube inlet overlap distance, and straight versus rounded ejector inlets. The relationship between the thrust augmentation results and various physical phenomena is described. To further understand the flow dynamics, shadow graph images of the exiting shock wave front from the PDE were also made. For the studied parameter space, the results showed a maximum augmentation of 40%. Further increase in augmentation is possible if the geometry of the ejector is tailored, a topic currently studied by numerous groups in the field.

Pal, S.; Santoro, Robert J.; Shehadeh, R.; Saretto, S.; Lee, S.-Y.

2005-01-01

273

Detonator cable initiation system safety investigation: Consequences of energizing the detonator and actuator cables  

SciTech Connect

This study was performed to explore and assess the worst-case response of a W89-type weapons system, damaged so as to expose detonator and/or detonator safing strong link (DSSL) cables to the most extreme, credible lightning-discharge, environment. The test program used extremely high-current-level, fast-rise-time (1- to 2-{mu}s) discharges to simulate lightning strikes to either the exposed detonator or DSSL cables. Discharges with peak currents above 700 kA were required to explode test sections of detonator cable and launch a flyer fast enough potentially to detonate weapon high explosive (HE). Detonator-safing-strong-link (DSSL) cables were exploded in direct contact with hot LX-17 and Ultrafine TATB (UFTATB). At maximum charging voltage, the discharge system associated with the HE firing chamber exploded the cables at more than 600-kA peak current; however, neither LX-17 nor UFTATB detonated at 250{degree}C. Tests showed that intense surface arc discharges of more than 700 kA/cm in width across the surface of hot UFTATB [generally the more sensitive of the two insensitive high explosives (IHE)] could not initiate this hot IHE. As an extension to this study, we applied the same technique to test sections of the much-narrower but thicker-cover-layer W87 detonator cable. These tests were performed at the same initial stored electrical energy as that used for the W89 study. Because of the narrower cable conductor in the W87 cables, discharges greater than 550-kA peak current were sufficient to explode the cable and launch a fast flyer. In summary, we found that lightning strikes to exposed DSSL cables cannot directly detonate LX-17 or UFTATB even at high temperatures, and they pose no HE safety threat.

Osher, J.; Chau, H.; Von Holle, W.

1994-03-01

274

Detonation energies of explosives by optimized JCZ3 procedures  

NASA Astrophysics Data System (ADS)

Procedures for the detonation properties of explosives have been extended for the calculation of detonation energies at adiabatic expansion conditions. The use of the JCZ3 equation of state with optimized Exp-6 potential parameters leads to lower errors in comparison to JWL detonation energies than for other methods tested.

Stiel, Leonard I.; Baker, Ernest L.

1998-07-01

275

A study on detonation characteristics of pressed NTO  

Microsoft Academic Search

NTO is an explosive of current interest. It has been evaluated as an insensitive component to replace RDX in some explosive and propellant compositions. In our work, efforts were made to determine NTO detonation pressure and JWL equation of state of NTO detonation products. With this end in view, pressed NTO cylinders were studied experimentally by measuring the detonation velocity

S. Cudzilo; W. A. Trzcinski

2001-01-01

276

Detonation Properties of Low-Sensitivity NTO-Based Explosives  

Microsoft Academic Search

Detonating performance of new explosive compositions containing NTO, TNT, RDX, and HMX is investigated in this work. Detonation velocity, pressure, and energy of the mixtures tested as well as acceleration ability and the equation of state of their detonation products were determined. Shock and impact sensitivities were evaluated in the gap test and heavy hammer test. Reaction of the mixtures

Waldemar A. Trzci?ski; Leszek Szyma?czyk

2005-01-01

277

Model for the Performance of Airbreathing Pulse-Detonation Engines  

Microsoft Academic Search

An analytical model for predicting the performance of a single-tube air-breathing pulse detonation engine has been developed. The model is based on control volume methods and elementary gas dynamics. The pulse detonation engine considered consists of a steady supersonic inlet, a large plenum, and a straight detonation tube (no exit nozzle). The fllling process is studied in detail through numerical

E. Wintenberger; J. E. Shepherd

2006-01-01

278

Experimental study of a pulse detonation rocket with Shchelkin spiral  

E-print Network

Experimental study of a pulse detonation rocket with Shchelkin spiral F.K. Lu, J.M. Meyers, and D There is much recent interest in the development of propulsion systems using high- frequency pulsed detonations facilities. This investigation explored the behavior of a Shchelkin spiral in a pulsed detonation engine

Texas at Arlington, University of

279

TRANSIENT FLOW ANALYSIS OF FILLING IN PULSE DETONATION  

E-print Network

TRANSIENT FLOW ANALYSIS OF FILLING IN PULSE DETONATION ENGINE by VEERA VENKATA SUNEEL JINNALA. November 20, 2009 #12;iv ABSTRACT TRANSIENT FLOW ANALYSIS OF FILLING IN PULSE DETONATION ENGINE Veera The Pulse Detonation Engine (PDE) is considered to be a propulsion system of future air vehicles

Texas at Arlington, University of

280

Detonation Properties of Ammonium Dinitramide (ADN)  

NASA Astrophysics Data System (ADS)

Ammonium Dinitramide, ADN, has a potential as an oxidizer for underwater high explosives. Pure ADN has a large reaction-zone length and shows a strong non-ideal behaviour. The work presented here is an extension of previous work.(Sensitivity and Performance Characterization of Ammonium Dinitramide (ADN). Presented at 11th International Detonation Symposium, Snowmass, CO, 1998.) Experiments for determining the detonation velocity as a function of inverse charge radius and density, reaction-zone length and curvature, and the detonation pressure are presented. Measurements of pressure indicates that no, or weak von-Neumann spike exists, suggesting an immediate chemical decomposition. Experimental data are compared with predicted using thermochemical codes and ZND-theory.

Wätterstam, A.; Östmark, H.; Helte, A.; Karlsson, S.

1999-06-01

281

Eigenvalue Detonation of Combined Effects Aluminized Explosives  

NASA Astrophysics Data System (ADS)

This paper reports on the development of theory and performance for recently developed combined effects aluminized explosives. Traditional high energy explosives used for metal pushing incorporate high loading percentages of HMX or RDX, whereas blast explosives incorporate some percentage of aluminum. However, the high blast explosives produce increased blast energies, with reduced metal pushing capability due to late time aluminum reaction. Metal pushing capability refers to the early volume expansion work produced during the first few volume expansions associated with cylinder wall velocities and Gurney energies. Our Recently developed combined effects aluminized explosives (PAX-29C, PAX-30, PAX-42) are capable of achieving excellent metal pushing and high blast energies. Traditional Chapman-Jouguet detonation theory does not explain the observed detonation states achieved by these combined effects explosives. This work demonstrates, with the use of cylinder expansion data and thermochemical code calculations (JAGUAR and CHEETAH), that eigenvalue detonation theory explains the observed behavior.

Capellos, Christos; Baker, Ernest; Balas, Wendy; Nicolich, Steven; Stiel, Leonard

2007-06-01

282

LATERALLY PROPAGATING DETONATIONS IN THIN HELIUM LAYERS ON ACCRETING WHITE DWARFS  

SciTech Connect

Theoretical work has shown that intermediate mass (0.01 M{sub Sun} < M{sub He} < 0.1 M{sub Sun }) helium shells will unstably ignite on the accreting white dwarf (WD) in an AM CVn binary. For more massive (M > 0.8 M{sub Sun }) WDs, these helium shells can be dense enough (>5 Multiplication-Sign 10{sup 5} g cm{sup -3}) that the convectively burning region runs away on a timescale comparable to the sound travel time across the shell, raising the possibility for an explosive outcome rather than an Eddington limited helium novae. The nature of the explosion (i.e., deflagration or detonation) remains ambiguous, is certainly density dependent, and likely breaks spherical symmetry. In the case of detonation, this causes a laterally propagating front whose properties in these geometrically thin and low-density shells we begin to study here. Our calculations show that the radial expansion time of <0.1 s leads to incomplete helium burning, in agreement with recent work by Sim and collaborators, but that the nuclear energy released is still adequate to realize a self-sustaining laterally propagating detonation. These detonations are slower than the Chapman-Jouguet speed of 1.5 Multiplication-Sign 10{sup 9} cm s{sup -1}, but still fast enough at 0.9 Multiplication-Sign 10{sup 9} cm s{sup -1} to go around the star prior to the transit through the star of the inwardly propagating weak shock. Our simulations resolve the subsonic region behind the reaction front in the detonation wave. The two-dimensional nucleosynthesis is shown to be consistent with a truncated one-dimensional Zeldovich-von Neumann-Doering calculation at the slower detonation speed. The ashes from the lateral detonation are typically He rich, and consist of predominantly {sup 44}Ti, {sup 48}Cr, along with a small amount of {sup 52}Fe, with very little {sup 56}Ni and with significant {sup 40}Ca in carbon-enriched layers. If this helium detonation results in a Type Ia supernova, its spectral signatures would appear for the first few days after explosion.

Townsley, Dean M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487-0324 (United States); Moore, Kevin; Bildsten, Lars, E-mail: Dean.M.Townsley@ua.edu [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States)

2012-08-10

283

Ignition-and-Growth Modeling of NASA Standard Detonator and a Linear Shaped Charge  

NASA Technical Reports Server (NTRS)

The main objective of this study is to quantitatively investigate the ignition and shock sensitivity of NASA Standard Detonator (NSD) and the shock wave propagation of a linear shaped charge (LSC) after being shocked by NSD flyer plate. This combined explosive train was modeled as a coupled Arbitrary Lagrangian-Eulerian (ALE) model with LS-DYNA hydro code. An ignition-and-growth (I&G) reactive model based on unreacted and reacted Jones-Wilkins-Lee (JWL) equations of state was used to simulate the shock initiation. Various NSD-to-LSC stand-off distances were analyzed to calculate the shock initiation (or failure to initiate) and detonation wave propagation along the shaped charge. Simulation results were verified by experimental data which included VISAR tests for NSD flyer plate velocity measurement and an aluminum target severance test for LSC performance verification. Parameters used for the analysis were obtained from various published data or by using CHEETAH thermo-chemical code.

Oguz, Sirri

2010-01-01

284

Computer modeling of electrical performance of detonators  

SciTech Connect

An empirical model of detonator electrical performance which describes the resistance of the exploding bridgewire (EBW) or exploding foil initiator (EFI or slapper) as a function of energy, deposition will be described. This model features many parameters that can be adjusted to obtain a close fit to experimental data. This has been demonstrated using recent experimental data taken with the cable discharge system located at Sandia National Laboratories. This paper will be a continuation of the paper entitled ``Cable Discharge System for Fundamental Detonator Studies`` presented at the 2nd NASA/DOD/DOE Pyrotechnic Workshop.

Furnberg, C.M. [Sandia National Labs., Livermore, CA (United States); Peevy, G.R.; Brigham, W.P.; Lyons, G.R. [Sandia National Labs., Albuquerque, NM (United States)

1995-05-01

285

Modeling Initiation in Exploding Bridgewire Detonators  

SciTech Connect

One- and two-dimensional models of initiation in detonators are being developed for the purpose of evaluating the performance of aged and modified detonator designs. The models focus on accurate description of the initiator, whether it be an EBW (exploding bridgewire) that directly initiates a high explosive powder or an EBF (exploding bridgefoil) that sends an inert flyer into a dense HE pellet. The explosion of the initiator is simulated using detailed MHD equations of state as opposed to specific action-based phenomenological descriptions. The HE is modeled using the best available JWL equations of state. Results to date have been promising, however, work is still in progress.

Hrousis, C A

2005-05-18

286

Numerical simulations of large-scale detonation tests in the RUT facility by the LES model.  

PubMed

The LES model based on the progress variable equation and the gradient method to simulate propagation of the reaction front within the detonation wave, which was recently verified by the ZND theory, is tested in this study against two large-scale experiments in the RUT facility. The facility was 27.6 m x 6.3 m x 6.55 m compartment with complex three-dimensional geometry. Experiments with 20% and 25.5% hydrogen-air mixture and different location of direct detonation initiation were simulated. Sensitivity of 3D simulations to control volume size and type were tested and found to be stringent compared to the planar detonation case. The maximum simulated pressure peak was found to be lower than the theoretical von Neumann spike value for the planar detonation and larger than the Chapman-Jouguet pressure thus indicating that it is more challenging to keep numerical reaction zone behind a leading front of numerical shock for curved fronts with large control volumes. The simulations demonstrated agreement with the experimental data. PMID:20541862

Zbikowski, Mateusz; Makarov, Dmitriy; Molkov, Vladimir

2010-09-15

287

Experimental Research on Induction Systems of an Air-breathing Valveless Pulse Detonation Engine  

NASA Astrophysics Data System (ADS)

An air-breathing valveless PDE model was designed and manufactured, which was made up of subsonic inlet, mixing chamber, ignition chamber, detonation chamber. The total pressure recovery coefficient, flux coefficient and intake resistance with six different induction systems were measured by a semi free subsonic flow field. The proof-of-principle experiments of PDE model with different induction systems were all successfully carried out, by using liquid gasoline-air mixture with low-energy system (total stored energy less than 50 mJ). The measured detonation wave pressure ratio was very close to that of C-J detonation. The air-breathing PDE model was easy to initiate and worked in good condition. The deflagration to detonation transition (DDT) and operation frequency effect on pressure traces were also investigated by experiments. The results indicated the oscillation of pressure peak at P6 enhanced with the operation frequency increased. DDT accomplished before P6 and the DDT distance was about 0.9 m (from the ignitor).

Wang, Zhi-wu; Chen, Xinggu; Zheng, Long-xi; Peng, Changxin; Yan, Chuan-jun

2012-06-01

288

Detonability of simple and representative components of pyrolysis products of kerosene: pulsed detonation engine application  

Microsoft Academic Search

The use of liquid fuels such as kerosene is of interest for the Pulse Detonation Engine (PDE). In this context, a representative\\u000a gaseous mixture of the lighter products resulting from the decomposition of a kerosene of type JP-10 was studied. The detonability\\u000a limits of simple components (hydrogen, ethylene, propylene) and mixtures of these components were tested in a 50 mm

X. Rocourt; P. Gillard; F. Faubert; I. Sochet; P. Dagaut

2005-01-01

289

Pressure Scaling Effects on Ignition and Detonation Initiation in a Pulse Detonation Engine  

Microsoft Academic Search

An experimental study was done to examine the effects of elevated initial tube pressure in the Pulse Detonation Engine (PDE). Measured parameters were the ignition time, deflagration to detonation transition (DDT) run-up distance, DDT times, and Chapman- Jouguet (C-J) velocity. Mixed with air, three fuels, i.e., aviation gasoline, ethylene, and hydrogen, were tested at various initial pressures and equivalence ratios.

Andrew Naples; Kenneth Busby; Frederick Schauer

290

Thermal degradation of two liquid fuels and detonation tests for pulse detonation engine studies  

Microsoft Academic Search

The use of liquid fuels such as kerosene is of interest for the pulse detonation engine (PDE). Within this context, the aim\\u000a of this work, which is a preliminary study, was to show the feasibility to initiate a detonation in air with liquid-fuel pyrolysis\\u000a products, using energies and dimensions of test facility similars to those of PDEs. Therefore, two liquids

X. Rocourt; P. Gillard; I. Sochet; D. Piton; A. Prigent

2007-01-01

291

Physicochemical model of detonation synthesis of nanoparticles from metal carboxylates  

NASA Astrophysics Data System (ADS)

We have shown previously that when metal carboxylates are subjected to a shock-wave action, diamond nanoparticles and nanoparticles of metals (Ag, Bi, Co, Fe, Pb) are formed and their characteristic size is about 30-200 Å. The metal nanoparticles formed are covered by an amorphous-carbon layer up to 20 Å thick. In this work we put forward a physicochemical model of the formation of diamond and metal nanoparticles from metal carboxylates upon shock-wave action. The energy released upon detonation inside the precursor is lower than in regions not occupied by the stearates. The characteristic time of temperature equalization has been estimated to be on the order of ˜10-3 s, which is greater by a factor of ˜103 than the characteristic reaction time. Due to the adiabatic nature of the processes occurring, the typical temperature of a "particle" will be lower than the temperature of the surrounding medium. In the framework of the model suggested, it has been assumed that the growth of metal clusters should occur by the diffusion mechanism; i.e., the "building material" is supplied through diffusion. The calculation using our previous experimental data on the reaction time and average size of metal particles has shown that the diffusion properties of the medium in which the metal nanoparticles are formed are close to those of the liquid state of the substance. The temperature and pressure under detonation conditions markedly exceed the analogous parameters characteristic of experiments on the thermodestruction of metal carboxylates. The small time of existence of the reaction mixture is compensated by the high mobility and concentration of reagents.

Tolochko, B. P.; Chernyshev, A. P.; Ten, K. A.; Pruuel, E. R.; Zhogin, I. L.; Zubkov, P. I.; Lyakhov, N. Z.; Luk'yanchikov, L. A.; Sheromov, M. A.

2008-02-01

292

Axisymmetric Numerical Modeling of Pulse Detonation Rocket Engines  

NASA Technical Reports Server (NTRS)

Pulse detonation rocket engines (PDREs) have generated research interest in recent years as a chemical propulsion system potentially offering improved performance and reduced complexity compared to conventional rocket engines. The detonative mode of combustion employed by these devices offers a thermodynamic advantage over the constant-pressure deflagrative combustion mode used in conventional rocket engines and gas turbines. However, while this theoretical advantage has spurred considerable interest in building PDRE devices, the unsteady blowdown process intrinsic to the PDRE has made realistic estimates of the actual propulsive performance problematic. The recent review article by Kailasanath highlights some of the progress that has been made in comparing the available experimental measurements with analytical and numerical models. In recent work by the author, a quasi-one-dimensional, finite rate chemistry CFD model was utilized to study the gasdynamics and performance characteristics of PDREs over a range of blowdown pressure ratios from 1-1000. Models of this type are computationally inexpensive, and enable first-order parametric studies of the effect of several nozzle and extension geometries on PDRE performance over a wide range of conditions. However, the quasi-one-dimensional approach is limited in that it cannot properly capture the multidimensional blast wave and flow expansion downstream of the PDRE, nor can it resolve nozzle flow separation if present. Moreover, the previous work was limited to single-pulse calculations. In this paper, an axisymmetric finite rate chemistry model is described and utilized to study these issues in greater detail. Example Mach number contour plots showing the multidimensional blast wave and nozzle exhaust plume are shown. The performance results are compared with the quasi-one-dimensional results from the previous paper. Both Euler and Navier-Stokes solutions are calculated in order to determine the effect of viscous effects in the nozzle flowfield. Additionally, comparisons of the model results to performance data from CalTech, as well as experimental flowfield measurements from Stanford University, are also reported.

Morris, Christopher I.

2005-01-01

293

DETERMINING DETONATION THRESHOLD FOR MULTIPLE FRAGMENT IMPACTS  

Microsoft Academic Search

Dual fragment impacts were studied using the Eulerian hydrocode CTH. The purposes of the study were to gain insight into the physical phenomena underlying multiple fragment impacts, and to develop an equation that predicts critical fragment velocity, the velocity at which a fragment must travel to cause a detonation in a covered explosive, for dual fragment impacts. Identical steel fragments

Lucia Kuhns; Leonard T. Wilson

294

Detonation product equation of state for Baratol  

Microsoft Academic Search

The metal acceleration ability of the composite explosive Baratol was experimentally determined using a Fabry Perot velocimeter. The Baratol reaction zone has a von Neuman spike pressure of 23.5 GPa. The performance of Baratol was found to be geometry dependent which is attributed to the slow reaction of barium nitrate's oxygen with the TNT detonation products. About 35% of the

J. W. Kury; R. D. Breithaupt

1989-01-01

295

Numerical Simulation of Pulse Detonation Engine Phenomena  

Microsoft Academic Search

This paper describes one- and two-dimensional numerical simulations, with simplified as well as full reaction kinetics, of a single cycle pulse detonation engine (PDE). The present studies explore the igni- tion energies associated with the initiation of a det- onation in the PDE tube, and quantify reactive flow phenomena, performance parameters, and noise gen- eration associated with full and simplified

Xing He; Ann R. Karagozian

2003-01-01

296

NOZZLE EFFECTS ON PULSE DETONATION ENGINES PERFORMANCE  

Microsoft Academic Search

Pulse detonation engine is a new concept across air-birthing propulsion systems. Today, due to the unsteady behavior of this type of engine, design optimizations are not completed yet. In this regard, recent studies are focused on the effects of nozzle implementation in this propulsion system. In this paper, the effect of nozzle shape (angle & length) on the impulse and

M. Arian; A. M. Tahsini

297

Magnetohydrodynamic Augmentation of Pulse Detonation Engines  

Microsoft Academic Search

Pulse detonation engines (PDEs) are the focus of increasing attention due to their potentially superior performance over constant pressure engines. Yet due to its unsteady chamber pressure, the PDE system will either be over- or under-expanded for the majority of the cycle, with energy being used without maximum gain. Magnetohydrodynamic (MHD) augmentation offers the opportunity to extract energy and apply

Christopher Zeineh; Lord Cole; Ann Karagozian

2010-01-01

298

Pulsed detonation engine experimental and theoretical review  

Microsoft Academic Search

A Review of past and current research on pulsed detonation engine devices connects early experimental work originating with the VI pulsejet to recent interest in such propulsion devices. The recent interest has been, in part, stimulated by Aviation Week where sightings of aircraft contrails lead to question if some sort of PDE device has already been developed. This review summarizes

Shmuel Eidelman; William Grossmann

1992-01-01

299

Artist's concept of Pulse Detonation Propulsion System  

NASA Technical Reports Server (NTRS)

Pictured is an artist's concept of an advanced chemical propulsion system called Pulse Detonation. Long term technology research in this advanced propulsion system has the potential to dramatically change the way we think about space propulsion systems. This research is expected to significantly reduce the cost of space travel within the next 25 years.

1999-01-01

300

Local Ignition in Carbon-Oxygen White Dwarfs. I. One-Zone Ignition and Spherical Shock Ignition of Detonations  

NASA Astrophysics Data System (ADS)

The details of ignition of Type Ia supernovae remain fuzzy, despite the importance of this input for any large-scale model of the final explosion. Here, we begin a process of understanding the ignition of these hot spots by examining the burning of one zone of material, and then we investigate the ignition of a detonation due to rapid heating at single point. We numerically measure the ignition delay time for onset of burning in mixtures of degenerate material and provide fitting formulae for conditions of relevance in the Type Ia problem. Using the neon abundance as a proxy for the white dwarf progenitor's metallicity, we then find that ignition times can decrease by ~20% with the addition of even 5% of neon by mass. When temperature fluctuations that successfully kindle a region are very rare, such a reduction in ignition time can increase the probability of ignition by orders of magnitude. If the neon comes largely at the expense of carbon, a similar decrease in the ignition time can occur. We then consider the ignition of a detonation by an explosive energy input in one localized zone, for example, a Sedov blast wave leading to a shock-ignited detonation. Building on previous work on curved detonations, we confirm that surprisingly large inputs of energy are required to successfully launch a detonation, leading to required match heads of ~4500 detonation thicknesses-tens of centimeters to hundreds of meters-which is orders of magnitude larger than naive considerations might suggest. This is a very difficult constraint to meet for some pictures of a deflagration-to-detonation transition, such as a Zel'dovich gradient mechanism ignition in the distributed burning regime.

Dursi, L. Jonathan; Timmes, F. X.

2006-04-01

301

Local Ignition in Carbon/Oxygen White Dwarfs - One-zone Ignition and Spherical Shock Ignition of Detonations  

NASA Astrophysics Data System (ADS)

The details of ignition of Type Ia supernovae remain fuzzy, despite the importance of this input for any large-scale model of the final explosion. Here, we begin a process of understanding the ignition of these hotspots by examining the burning of one zone of material, and then investigate the ignition of a detonation due to rapid heating at single point.We numerically measure the ignition delay time for onset of burning in mixtures of degenerate material and provide fitting formula for conditions of relevance in the Type Ia problem. Using the neon abundance as a proxy for the white dwarf progenitor’s metallicity, we then find that ignition times can decrease by over 20% with addition of even 5% of neon by mass. When temperature fluctuations that successfully kindle a region are very rare, such a reduction in ignition time can increase the probability of ignition by orders of magnitude. If the neon comes largely at the expense of carbon, a similar decrease in the ignition time can occur.We then consider the ignition of a detonation by an explosive energy input in one localized zone, e.g. a Sedov blast wave leading to a shock-ignited detonation. Building on previous work on curved detonations, we confirm that surprisingly large inputs of energy are required to successfully launch a detonation, leading to required matchheads of 4500 detonation thicknesses - tens of centimeters to hundreds of meters - which is orders of magnitude larger than naive considerations might suggest. This is a very difficult constraint to meet for some pictures of a deflagration-to-detonation transition, such as a Zel’dovich gradient mechanism ignition in the distributed burning regime.

Dursi, L. J.; Timmes, F. X.

2006-06-01

302

Laser-supported partial laparoscopic nephrectomy for renal cell carcinoma without ischaemia time  

PubMed Central

Background To date, elective nephron-sparing surgery is an established method for the exstirpation of renal tumors. While open partial nephrectomy remains the reference standard of the management of renal masses, laparoscopic partial nephrectomy (LPN) continues to evolve. Conventional techniques include clamping the renal vessels risking ischaemic damage of the clamped organ. Thus, new techniques are needed that combine a sufficient tissue incision for exstirpation of the tumor with an efficient coagulation to assure haemostasis and abandon renal vessel clamping in LPN. Laser-excision of renal tumors during laparoscopic surgery seems to be a logical solution. Methods We performed nephron-sparing surgery without clamping of the renal vessels in 11 patients with a renal tumor in exophytic position (mean size 32 mm, ranging 8–45 mm) by laser-supported LPN. Results Regular ultrasound monitoring and insertion of a temporary drainage showed no evidence of postoperative hemorrhage. All tumors were removed with a histopathologically confirmed surrounding margin of normal renal tissue (R0 resection). Serum creatinine, hemoglobin, and hematocrit were nearly unaltered before and after surgery. Conclusions The experience won in these patients have confirmed that laser-assisted LPN without clamping of the renal vessels could be a safe and gentle alternative to classic partial nephrectomy in patients with exophytic position of renal tumors. PMID:23786969

2013-01-01

303

Proton radiography of PBX 9502 detonation shock dynamics confinement sandwich test  

SciTech Connect

Recent results utilizing proton radiography (P-Rad) during the detonation of the high explosive PBX 9502 are presented. Specifically, the effects of confinement of the detonation are examined in the LANL detonation confinement sandwich geometry. The resulting detonation velocity and detonation shock shape are measured. In addition, proton radiography allows one to image the reflected shocks through the detonation products. Comparisons are made with detonation shock dynamics (DSD) and reactive flow models for the lead detonation shock and detonation velocity. In addition, predictions of reflected shocks are made with the reactive flow models.

Aslam, Tariq D [Los Alamos National Laboratory; Jackson, Scott I [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory

2009-01-01

304

Effects of void size, density, and arrangement on deflagration and detonation sensitivity of a reactive empirical bond order high explosive  

NASA Astrophysics Data System (ADS)

The shock response of two-dimensional model high explosive crystals with various arrangements of circular voids is explored. We simulate a piston impact using molecular-dynamics simulations with a reactive empirical bond order model potential for a submicron, subnanosecond exothermic reaction in a diatomic molecular solid. Voids of radius 10 nm reduce the minimum initiating velocity by a factor of 4; a single 2.5 nm void (per periodic image) reduces the minimum velocity for detonation by 10% and the exponent of the induction time’s pressure dependence by about 4. In square lattices of voids all of one size, reducing that size or increasing the porosity while holding the other parameter fixed causes the hotspots to consume the material more quickly and detonation to occur sooner and at lower piston velocities. The early time behavior is seen to follow a very simple ignition and growth model. The hotspots collectively develop a broad pressure wave (a sonic, diffuse deflagration front) that, upon merging with the lead shock, transforms it into a detonation. The reaction yields produced by triangular lattices are not significantly different. With random void arrangements, the mean time to detonation is 15.5% larger than with the square lattice; the standard deviation of detonation delays is just 5.1%.

Herring, S. Davis; Germann, Timothy C.; Grønbech-Jensen, Niels

2010-12-01

305

Shock initiation and detonation study on high concentration H2O2/H2O solutions using in-situ magnetic gauges  

SciTech Connect

Concentrated hydrogen peroxide (H{sub 2}O{sub 2}) has been known to detonate for many years. However, because of its reactivity and the difficulty in handling and confining it, along with the large critical diameter, few studies providing basic information about the initiation and detonation properties have been published. We are conducting a study to understand and quantify the initiation and detonation properties of highly concentrated H{sub 2}O{sub 2} using a gas-driven two-stage gun to produce well defined shock inputs. Multiple magnetic gauges are used to make in-situ measurements of the growth of reaction and subsequent detonation in the liquid. These experiments are designed to be one-dimensional to eliminate any difficulties that might be encountered with large critical diameters. Because of the concern of the reactivity of the H{sub 2}O{sub 2} with the confining materials, a remote loading system has been developed. The gun is pressurized, then the cell is filled and the experiment shot within less than three minutes. Several experiments have been completed on {approx}98 wt % H{sub 2}O{sub 2}/H{sub 2}O mixtures; homogeneous shock initiation behavior has been observed in the experiments where reaction is observed. The initial shock pressurizes and heats the mixture. After an induction time, a thermal explosion type reaction produces an evolving reactive wave that strengthens and eventually overdrives the first wave producing a detonation. From these experiments, we have determined unreacted Hugoniot points, times-to-detonation points that indicate low sensitivity (an input of 13.5 GPa produces detonation in 1 {micro}s compared to 9.5 GPa for neat nitromethane), and detonation velocities of high concentration H{sub 2}O{sub 2}/H{sub 2}O solutions of over 6.6 km/s.

Sheffield, Stephen A [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Stahl, David B [Los Alamos National Laboratory; Gibson, L Lee [Los Alamos National Laboratory; Bartram, Brian D [Los Alamos National Laboratory; Engelke, Ray [Los Alamos National Laboratory

2010-01-01

306

Fracture response of externally flawed aluminum cylindrical shells under internal gaseous detonation loading  

E-print Network

. Shepherd deliberately loaded by detonations such as pulse detonation engines and gaseous detonation tubes or detonation loading (ASME, 2000). Engineering applications include tubes that are c 2005 Kluwer Academic detonation loading Tong Wa Chao and Joseph E. Shepherd Graduate Aeronautical Laboratories, California

Barr, Al

307

Anomalous shock initiation of detonation in pentaerythritol tetranitrate crystals  

SciTech Connect

The anomalous, low-stress, shock initiation of detonation observed in earlier studies of pentaerythritol tetranitrate single crystals was examined in more detail experimentally. Time-resolved particle-velocity histories were obtained for [110], [001] and [100] orientations of single-crystal pentaerythritol tetranitrate explosive for shock input stresses of 4{endash}7 GPa using laser interferometry instrumentation. At about 4.2 GPa an elastic-plastic, two-wave structure was noted in [110] and [001] orientations, and a single shock wave for [100] orientation. The two-wave structure provides an explanation for the anomalous shock initiation sensitivity and intermediate velocity transition previously observed in [110] orientation at this stress level. It also explains details of fluorescent emission histories from [110] and [001] crystals previously measured. The orientation-dependent results are consistent with the model of steric hindrance to shear at the molecular level. Fits to the elastic Hugoniot data in [110] and [001] orientations are given as well as a revised fit for the bulk Hugoniot. {copyright} {ital 1997 American Institute of Physics.}

Dick, J.J. [MS P952, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [MS P952, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-01-01

308

Time variation in the reaction-zone structure of two-phase spray detonations.  

NASA Technical Reports Server (NTRS)

A detailed theoretical analysis of the time-varying detonation structure in a monodisperse spray is presented. The theory identifies experimentally observed reaction-zone overpressures as deriving from blast waves formed therein by the explosive ignition of the spray droplets, and follows in time the motion, change in strength, and interactions of these blast waves with one another, and with the leading shock. The results are compared with experimental data by modeling the motion of a finite-size circular pressure transducer through the theoretical data field in an x-t space.

Pierce, T. H.; Nicholls, J. A.

1973-01-01

309

Mesoscopic simulations of shock-to-detonation transition in reactive liquid high explosive  

NASA Astrophysics Data System (ADS)

An extension of the model described in a previous work (see Maillet J. B. et al., EPL, 78 (2007) 68001) based on Dissipative Particle Dynamics is presented and applied to a liquid high explosive (HE), with thermodynamic properties mimicking those of liquid nitromethane. Large scale nonequilibrium simulations of reacting liquid HE with model kinetic under sustained shock conditions allow a better understanding of the shock-to-detonation transition in homogeneous explosives. Moreover, the propagation of the reactive wave appears discontinuous since ignition points in the shocked material can be activated by the compressive waves emitted from the onset of chemical reactions.

Maillet, J. B.; Bourasseau, E.; Desbiens, N.; Vallverdu, G.; Stoltz, G.

2011-12-01

310

Laser High-Cycle Thermal Fatigue of Pulse Detonation Engine Combustor Materials Tested  

NASA Technical Reports Server (NTRS)

Pulse detonation engines (PDE's) have received increasing attention for future aerospace propulsion applications. Because the PDE is designed for a high-frequency, intermittent detonation combustion process, extremely high gas temperatures and pressures can be realized under the nearly constant-volume combustion environment. The PDE's can potentially achieve higher thermodynamic cycle efficiency and thrust density in comparison to traditional constant-pressure combustion gas turbine engines (ref. 1). However, the development of these engines requires robust design of the engine components that must endure harsh detonation environments. In particular, the detonation combustor chamber, which is designed to sustain and confine the detonation combustion process, will experience high pressure and temperature pulses with very short durations (refs. 2 and 3). Therefore, it is of great importance to evaluate PDE combustor materials and components under simulated engine temperatures and stress conditions in the laboratory. In this study, a high-cycle thermal fatigue test rig was established at the NASA Glenn Research Center using a 1.5-kW CO2 laser. The high-power laser, operating in the pulsed mode, can be controlled at various pulse energy levels and waveform distributions. The enhanced laser pulses can be used to mimic the time-dependent temperature and pressure waves encountered in a pulsed detonation engine. Under the enhanced laser pulse condition, a maximum 7.5-kW peak power with a duration of approximately 0.1 to 0.2 msec (a spike) can be achieved, followed by a plateau region that has about one-fifth of the maximum power level with several milliseconds duration. The laser thermal fatigue rig has also been developed to adopt flat and rotating tubular specimen configurations for the simulated engine tests. More sophisticated laser optic systems can be used to simulate the spatial distributions of the temperature and shock waves in the engine. Pulse laser high-cycle thermal fatigue behavior has been investigated on a flat Haynes 188 alloy specimen, under the test condition of 30-Hz cycle frequency (33-msec pulse period and 10-msec pulse width including a 0.2-msec pulse spike; ref. 4). Temperature distributions were calculated with one-dimensional finite difference models. The calculations show that that the 0.2-msec pulse spike can cause an additional 40 C temperature fluctuation with an interaction depth of 0.08 mm near the specimen surface region. This temperature swing will be superimposed onto the temperature swing of 80 C that is induced by the 10-msec laser pulse near the 0.53-mm-deep surface interaction region.

Zhu, Dong-Ming; Fox, Dennis S.; Miller, Robert A.

2001-01-01

311

Numerical study of sidewall filling for gas-fed pulse detonation engines  

NASA Astrophysics Data System (ADS)

Pulse detonation engines for aerospace propulsion are required to operate at 50-100 Hz meaning that each pulse is 10-20 ms long. Filling of the engine and the related purging process become dominant due to their long duration compared to ignition and detonation wave propagation. This study uses ANSYS FLUENT to investigate the filling of a 1 m long tube with an internal diameter of 100 mm. Six different configurations were investigated with an endwall port and various sidewall arrangements, including stagger and inclination. A stoichiometric mixture of gaseous octane and air at STP was used to fill the tube at injection rates of 40, 150 and 250 m/s. Phase injection was also investigated and it showed performance improvements such as reduced lling time and reduced propellant escape from the exit.

Rongrat, Wunnarat

312

Performance and environmental impact assessment of pulse detonation based engine systems  

NASA Astrophysics Data System (ADS)

Experimental research was performed to investigate the feasibility of using pulse detonation based engine systems for practical aerospace applications. In order to carry out this work a new pulse detonation combustion research facility was developed at the University of Cincinnati. This research covered two broad areas of application interest. The first area is pure PDE applications where the detonation tube is used to generate an impulsive thrust directly. The second focus area is on pulse detonation based hybrid propulsion systems. Within each of these areas various studies were performed to quantify engine performance. Comparisons of the performance between detonation and conventional deflagration based engine cycles were made. Fundamental studies investigating detonation physics and flow dynamics were performed in order to gain physical insight into the observed performance trends. Experimental studies were performed on PDE-driven straight and diverging ejectors to determine the system performance. Ejector performance was quantified by thrust measurements made using a damped thrust stand. The effects of PDE operating parameters and ejector geometric parameters on thrust augmentation were investigated. For all cases tested, the maximum thrust augmentation is found to occur at a downstream ejector placement. The optimum ejector geometry was determined to have an overall length of LEJECT/DEJECT =5.61, including an intermediate-straight section length of LSTRT /DEJECT=2, and diverging exhaust section with 4 deg half-angle. A maximum thrust augmentation of 105% was observed while employing the optimized ejector geometry and operating the PDE at a fill-fraction of 0.6 and a frequency of 10 Hz. When operated at a fill-fraction of 1.0 and a frequency of 30 Hz, the thrust augmentation of the optimized PDE-driven ejector system was observed to be 71%. Static pressure was measured along the interior surface of the ejector, including the inlet and exhaust sections. The diverging ejector pressure distribution shows that the diverging section acts as a subsonic diffuser. To provide a better explanation of the observed performance trends, shadowgraph images of the detonation wave and starting vortex interacting with the ejector inlet were obtained. The acoustic signature of a pulse detonation engine was characterized in both the near-field and far-field regimes. Experimental measurements were performed in an anechoic test facility designed for jet noise testing. Both shock strength and speed were mapped as a function of radial distance and direction from the PDE exhaust plane. It was found that the PDE generated pressure field can be reasonably modeled by a theoretical point-source explosion. The effect of several exit nozzle configurations on the PDE acoustic signature was studies. These included various chevron nozzles, a perforated nozzle, and a set of proprietary noise attenuation mufflers. Experimental studies were carried out to investigate the performance of a hybrid propulsion system integrating an axial flow turbine with multiple pulse detonation combustors. The integrated system consisted of a circular array of six pulse detonation combustor (PDC) tubes exhausting through an axial flow turbine. Turbine component performance was quantified by measuring the amount of power generated by the turbine section. Direct comparisons of specific power output and turbine efficiency between a PDC-driven turbine and a turbine driven by steady-flow combustors were made. It was found that the PDC-driven turbine had comparable performance to that of a steady-burner-driven turbine across the operating map of the turbine.

Glaser, Aaron J.

313

Prompt Reaction of Aluminum in Detonating Explosives  

NASA Astrophysics Data System (ADS)

The potential of aluminum (Al) reaction to boost detonation energy has been studied for decades, most recently spurred by the availability of nanometer-sized particles. A literature review is consistent with results from the small-scale shock reactivity test (SSRT). In this test, <1/2-g samples in confinement are shock loaded on one end, and the output at the other end dents a soft witness block. For samples in which 0.3 g of cyclotetramethylenetetranitramine (HMX) was mixed with 8 ?m Al, the deepest dent occurred at 15% Al. When ammonium perchlorate (AP) was mixed with the same Al, the increased dents were consistent with changes in detonation velocity previously reported on similar mixtures. One outcome of this study is a new interpretation for the participation of Al in large scale gap tests on plastic-bonded explosives, which was discussed by Bernecker at this meeting in 1987.

Sandusky, H. W.; Granholm, R. H.

2006-07-01

314

Heat of detonation, the cylinder test, and performance munitions  

SciTech Connect

Heats of detonation of CHNO explosives correlate well with copper cylinder test expansion data. The detonation products/calorimetry data can be used to estimate performance in the cylinder test, in munitions, and for new molecules or mixtures of explosives before these are made. Confidence in the accuracy of the performance estimates is presently limited by large deviations of a few materials from the regression predictions; but these same deviations, as in the insensitive explosive DINGU and the low carbon systems, appear to be sources of information useful for detonation and explosives research. The performance correlations are functions more of the detonation products and thermochemical energy than they are of the familiar parameters of detonation pressure and velocity, and the predictions are closer to a regression line on average than are those provided by CJ calculations. The prediction computations are simple but the measurements (detonation calorimetry/products and cylinder experiments) are not. 17 refs., 5 tabs.

Akst, I.B.

1989-01-01

315

DSD front models: nonideal explosive detonation in ANFO  

SciTech Connect

The DSD method for modeling propagating detonation is based on three elements: (1) a subscale theory of multi-dimensional detonation that treats the detonation as a front whose dynamics depends only on metrics of the front (such as curvature, etc.), (2) high-resolution, direct numerical simulation of detonation using Euler equation models, and (3) physical experiments to characterize multi-dimensional detonation propagation in real explosives and to provide data to calibrate DSD front models. In this paper, we describe our work on elements (1) and (3), develop a DSD calibration for the nonideal explosive ANFO and then demonstrate the utility of the ANFO calibration, with an example 3D detonation propagation calculation.

Bdzil, J. B. (John Bohdan); Aslam, T. D. (Tariq D.); Catanach, R. A. (Richard A.); Hill, L. G. (Larry G.); Short, M. (Mark Short)

2002-01-01

316

Equation of state for detonation products  

SciTech Connect

An equation of state for detonation products, with the usual form p = p(v,E), is proposed. It allows independent calibration of the adiabatic gamma and the Grueneisen gamma, and gives them forms in agreement with recent theoretical studies. The equation of state is given by p = E/v[k [minus] 1 + F(v) [l brace]1 + b(1 [minus] E/E[sup s](v))[r brace

Davis, W.C.

1993-01-01

317

PULSED DETONATION ENGINE PROCESSES: EXPERIMENTS AND SIMULATIONS  

Microsoft Academic Search

Computational and experimental investigations of a pulsed detonation engine (PDE) operating in a cycle using ethylene\\/air mixtures are reported. Simulations are performed for two geometry configurations, namely, an ideal tube PDE with a smooth wall fueled with premixed C2H4\\/O2 and a benchmark tube PDE with internal geometry and a valveless air supply fueled with C2H4. Performance estimates of fuel-specific impulse

V. E. TANGIRALA; A. J. DEAN; D. M. CHAPIN; P. F. PINARD; B. VARATHARAJAN

2004-01-01

318

Jet initiation of deflagration and detonation  

Microsoft Academic Search

We have constructed a facility for the study of jet-initiated deflagration and detonation in hydrogen-air-steam mixtures. The facility is built around two pressure vessels. Mixtures of hydrogen, oxygen and nitrogen are spark-ignited in the driver vessel, generating a hot mixture of combustion products. The pressure rise ruptures a diaphragm, venting the products into the receiver vessel through nozzles of 12.7-92

James Christopher Krok

1997-01-01

319

Hydrodynamic Detonation Instability in Electroweak and QCD Phase Transitions  

E-print Network

The hydrodynamic stability of deflagration and detonation bubbles for a first order electroweak and QCD phase transition has been discussed recently with the suggestion that detonations are stable. We examine here the case of a detonation more carefully. We find that in front of the bubble wall perturbations do not grow with time, but behind the wall modes exist which grow exponentially. We briefly discuss the possible meaning of this instability.

Mark Abney

1993-05-18

320

Future Modeling Needs in Pulse Detonation Rocket Engine Design  

NASA Technical Reports Server (NTRS)

This paper presents a performance model rocket engine design that takes advantage of pulse detonation to generate thrust. The contents include: 1) Introduction to the Pulse Detonation Rocket Engine (PDRE); 2) PDRE modeling issues and options; 3) Discussion of the PDRE Performance Workshop held at Marshall Space Flight Center; and 4) Identify needs involving an open performance model for Pulse Detonation Rocket Engines. This paper is in viewgraph form.

Meade, Brian; Talley, Doug; Mueller, Donn; Tew, Dave; Guidos, Mike; Seymour, Dave

2001-01-01

321

Experimental Study of Key Issues on Pulse Detonation Engine Development  

Microsoft Academic Search

An experimental study on the pulse detonation engine (PDE) is conducted using hydrogen-air mixtures. Several key issues for PDE development, including valve operation, injection, mixing, filling, cycle repetition, ignition timing, DDT distance and propagation of detonation\\/quasi-detonation, are investigated. The fuel and oxidizer are injected into the PDE from opposite sidewall directions so as to be well mixed by collision of

Feng-Yuan Zhang; Toshitaka Fujiwara; Takeshi Miyasaka; Ei-Ichi Nakayama; Tsuyoshi Hattori; Nobuyuki Azuma; Satoru Yoshida; Azusa Tamugi

2005-01-01

322

Detonation of Meta-stable Clusters  

SciTech Connect

We consider the energy accumulation in meta-stable clusters. This energy can be much larger than the typical chemical bond energy (~;;1 ev/atom). For example, polymeric nitrogen can accumulate 4 ev/atom in the N8 (fcc) structure, while helium can accumulate 9 ev/atom in the excited triplet state He2* . They release their energy by cluster fission: N8 -> 4N2 and He2* -> 2He. We study the locus of states in thermodynamic state space for the detonation of such meta-stable clusters. In particular, the equilibrium isentrope, starting at the Chapman-Jouguet state, and expanding down to 1 atmosphere was calculated with the Cheetah code. Large detonation pressures (3 and 16 Mbar), temperatures (12 and 34 kilo-K) and velocities (20 and 43 km/s) are a consequence of the large heats of detonation (6.6 and 50 kilo-cal/g) for nitrogen and helium clusters respectively. If such meta-stable clusters could be synthesized, they offer the potential for large increases in the energy density of materials.

Kuhl, Allen; Kuhl, Allen L.; Fried, Laurence E.; Howard, W. Michael; Seizew, Michael R.; Bell, John B.; Beckner, Vincent; Grcar, Joseph F.

2008-05-31

323

Kinetic information from detonation front curvature  

SciTech Connect

The time constants for time-dependent modeling may be estimated from reaction zone lengths, which are obtained from two sources One is detonation front curvature, where the edge lag is close to being a direct measure The other is the Size Effect, where the detonation velocity decreases with decreasing radius as energy is lost to the cylinder edge A simple theory that interlocks the two effects is given A differential equation for energy flow in the front is used, the front is described by quadratic and sixth-power radius terms The quadratic curvature comes from a constant power source of energy moving sideways to the walls Near the walls, the this energy rises to the total energy of detonation and produces the sixth-power term The presence of defects acting on a short reaction zone can eliminate the quadratic part while leaving the wall portion of the cuvature A collection of TNT data shows that the reaction zone increases with both the radius and the void fraction

Souers, P. C., LLNL

1998-06-15

324

Hydroxyapatite Reinforced Coatings with Incorporated Detonationally Generated Nanodiamonds  

SciTech Connect

We studied the effect of the substrate chemistry on the morphology of hydroxyapatite-detonational nanodiamond composite coatings grown by a biomimetic approach (immersion in a supersaturated simulated body fluid). When detonational nanodiamond particles were added to the solution, the morphology of the grown for 2 h composite particles was porous but more compact then that of pure hydroxyapatite particles. The nanodiamond particles stimulated the hydroxyapatite growth with different morphology on the various substrates (Ti, Ti alloys, glasses, Si, opal). Biocompatibility assay with MG63 osteoblast cells revealed that the detonational nanodiamond water suspension with low and average concentration of the detonational nanodiamond powder is not toxic to living cells.

Pramatarova, L.; Pecheva, E.; Hikov, T.; Fingarova, D. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Sofia (Bulgaria); Dimitrova, R. [Institute of Organic Chemistry with Centre of Phytochemistry, Sofia (Bulgaria); Spassov, T. [Faculty of Chemistry, Sofia University, Sofia (Bulgaria); Krasteva, N. [Institute of Biophysics, Bulgarian Academy of Science, Sofia (Bulgaria); Mitev, D. [Space Research Institute, Bulgarian Academy of Sciences, Sofia (Bulgaria)

2010-01-21

325

Safety and performance enhancement circuit for primary explosive detonators  

DOEpatents

A safety and performance enhancement arrangement for primary explosive detonators. This arrangement involves a circuit containing an energy storage capacitor and preset self-trigger to protect the primary explosive detonator from electrostatic discharge (ESD). The circuit does not discharge into the detonator until a sufficient level of charge is acquired on the capacitor. The circuit parameters are designed so that normal ESD environments cannot charge the protection circuit to a level to achieve discharge. When functioned, the performance of the detonator is also improved because of the close coupling of the stored energy.

Davis, Ronald W. (Tracy, CA)

2006-04-04

326

A library of prompt detonation reaction zone data  

SciTech Connect

Tables are given listing literature data that allows calculation of sonic reaction zones at or near steady-state for promptly detonating explosive cylinders. The data covers homogeneous, heterogeneous, composite, inorganic and binary explosives and allows comparison across the entire explosive field. Table 1 lists detonation front curvatures. Table 2 lists Size Effect data, i.e. the change of detonation velocity with cylinder radius. Table 3 lists failure radii and detonation velocities. Table 4 lists explosive compositions. A total of 51 references dating back into the 1950`s are given. Calculated reaction zones, radii of curvature and growth rate coefficients are listed.

Souers, P. C., LLNL

1998-06-01

327

Detonation shock dynamics calibration for non-ideal HE: ANFO  

SciTech Connect

Linear D{sub n}-{kappa} detonation shock dynamics (DSD) filling forms are obtained for four ammonium nitrate-fuel oil (ANFO) mixtures involving variations in the ammonium nitrate prill properties and ANFO stoichiometries. The detonation of ammonium nitrate-fuel oil (ANFO) mixtures is considered to be highly nonideal involving long reaction zones ({approx} several cms), low detonation energies and large failure diameters ({approx} 10s-100s cms). A number of experimental programs have been undertaken to understand ANFO detonation properties as a function of the AN properties [1]-[7]. Given the highly heterogeneous nature of ANFO mixtures (typical high explosive (HE) grade AN prills are porous with a range of diameters) a predictive reactive flow simulation of ANFO detonation will present significant challenges. At Los Alamos, a simulation capability has been developed for predicting the propagation of detonation in non-ideal HE and the work conducted on surrounding materials via a combination of a detonation shock dynamics (DSD) approach and a modified programmed burn method known as the pseudo-reaction-zone (or PRZ) method that accounts for the long detonation reaction zone. In the following, linear D{sub n}-{kappa} DSD fitting forms are obtained for four ammonium nitrate-fuel oil mixtures involving variation in the ammonium nitrate prill properties and ANFO stoichiometries. A detonation shock dynamics calibration for ANFO consisting of regular porous HE grade AN in a 94/6 wt.% AN to FO mix has been obtained in [7].

Short, Mark [Los Alamos National Laboratory; Salyer, Terry R [Los Alamos National Laboratory; Aslam, Tariq D [Los Alamos National Laboratory; Kiyanda, Charles B [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory; Zimmerley, Tony [NEW MEXICO TECH

2009-01-01

328

Experimental study of the detonation of technical grade ammonium nitrate  

NASA Astrophysics Data System (ADS)

The detonation of technical grade ammonium nitrate at the density ?=0.666 g/cm confined in PVC and steel tubes was experimentally studied. The results show that the detonation is self-sustained and steady in steel tubes with diameter as small as 12 mm. Critical detonation diameter lies between 8 and 12 mm in 2 mm thick steel tubes and between 55 and 81 mm in PVC tubes. These values testify a strong detonation sensitivity of this product. To cite this article: H.-N. Presles et al., C. R. Mecanique 337 (2009).

Presles, Henri-Noël; Vidal, Pierre; Khasainov, Boris

2009-11-01

329

Detonation Shock Dynamics Calibration for Non-Ideal HE: ANFO  

NASA Astrophysics Data System (ADS)

The detonation of ammonium nitrate (AN) and fuel-oil (FO) mixtures (ANFO) is significantly influenced by the properties of the AN (porosity, particle size, coating) and fuel-oil stoichiometry. We report on a new series of rate-stick experiments in cardboard confinement that highlight detonation front speed and curvature dependence on AN/FO stoichiometry and AN particle properties. Standard detonation velocity-curvature calibrations to the experimental data will be presented, as well as higher-order time-dependent detonation shock dynamics calibrations.

Short, Mark; Salyer, Terry

2009-06-01

330

Simulation of the Reflected Blast Wave froma C-4 Charge  

SciTech Connect

The reflection of a blast wave from a C4 charge detonated above a planar surface is simulated with our ALE3D code. We used a finely-resolved, fixed Eulerian 2-D mesh (167 {micro}m per cell) to capture the detonation of the charge, the blast wave propagation in nitrogen, and its reflection from the surface. The thermodynamic properties of the detonation products and nitrogen were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. Computed pressure histories are compared with pressures measured by Kistler 603B piezoelectric gauges at 8 ranges (GR = 0, 2, 4, 8, 10, and 12 inches) along the reflecting surface. Computed and measured waveforms and positive-phase impulses were similar, except at close-in ranges (GR < 2 inches), which were dominated by jetting effects.

Howard, W M; Kuhl, A L; Tringe, J W

2011-08-01

331

A flash vaporization system for detonation of hydrocarbon fuels in a pulse detonation engine  

NASA Astrophysics Data System (ADS)

Current research by both the US Air Force and Navy is concentrating on obtaining detonations in a pulse detonation engine (PDE) with low vapor pressure, kerosene based jet fuels. These fuels, however, have a low vapor pressure and the performance of a liquid hydrocarbon fueled PDE is significantly hindered by the presence of fuel droplets. A high pressure, fuel flash vaporization system (FVS) has been designed and built to reduce and eliminate the time required to evaporate the fuel droplets. Four fuels are tested: n-heptane, isooctane, aviation gasoline, and JP-8. The fuels vary in volatility and octane number and present a clear picture on the benefits of flash vaporization. Results show the FVS quickly provided a detonable mixture for all of the fuels tested without coking or clogging the fuel lines. Combustion results validated the model used to predict the fuel and air temperatures required to achieve gaseous mixtures with each fuel. The most significant achievement of the research was the detonation of flash vaporized JP-8 and air. The results show that the flash vaporized JP-8 used 20 percent less fuel to ignite the fuel air mixture twice as fast (8 ms from 16 ms) when compared to the unheated JP-8 combustion data. Likewise, the FVS has been validated as a reliable method to create the droplet free mixtures required for liquid hydrocarbon fueled PDEs.

Tucker, Kelly Colin

332

The hypervelocity hot subdwarf US 708 - remnant of a double-detonation SN Ia?  

NASA Astrophysics Data System (ADS)

Type Ia supernovae {SN Ia} are the most important standard candles for measuring the expansion history of the universe. The thermonuclear explosion of a white dwarf can explain their observed properties, but neither the progenitor systems nor any stellar remnants have been conclusively identified. Underluminous SN Ia have been proposed to originate from a so-called double-detonation of a white dwarf. After a critical amount of helium is deposited on the surface through accretion from a close companion, the helium is ignited causing a detonation wave that triggers the explosion of the white dwarf itself. The helium star will then be ejected at so large a velocity that it will escape the Galaxy. The predicted properties of this remnant are an excellent match to the so-called hypervelocity star US 708, a hot, helium-rich star moving at more than 750 km/s, sufficient to leave the Galaxy.Here we propose medium-resolution COS spectroscopy to measure the vsini of the hypervelocity He-sdO US 708 for the first time and to search for abundance anomalies caused by pollution through an SN Ia event. This will allow us to test the double-detonation scenario with sdB donor empirically.

Geier, Stephan

2013-10-01

333

Mechanisms of detonation formation due to a temperature gradient  

Microsoft Academic Search

Emergence of a detonation in a homogeneous, exothermically reacting medium can be deemed to occur in two phases. The first phase processes the medium so as to create conditions ripe for the onset of detonation. The actual events leading up to preconditioning may vary from one experiment to the next, but typically, at the end of this stage the medium

A. K. Kapila; D. W. Schwendeman; J. J. Quirk; T. Hawa

2002-01-01

334

Effects of Fuel Distribution on Detonation Tube Performance  

NASA Technical Reports Server (NTRS)

A pulse detonation engine (PDE) uses a series of high frequency intermittent detonation tubes to generate thrust. The process of filling the detonation tube with fuel and air for each cycle may yield non-uniform mixtures. Lack of mixture uniformity is commonly ignored when calculating detonation tube thrust performance. In this study, detonation cycles featuring idealized non-uniform H2/air mixtures were analyzed using the SPARK two-dimensional Navier-Stokes CFD code with 7-step H2/air reaction mechanism. Mixture non-uniformities examined included axial equivalence ratio gradients, transverse equivalence ratio gradients, and partially fueled tubes. Three different average test section equivalence ratios (phi), stoichiometric (phi = 1.00), fuel lean (phi = 0.90), and fuel rich (phi = 1.10), were studied. All mixtures were detonable throughout the detonation tube. It was found that various mixtures representing the same test section equivalence ratio had specific impulses within 1 percent of each other, indicating that good fuel/air mixing is not a prerequisite for optimal detonation tube performance.

Perkins, Hugh Douglas

2002-01-01

335

Proof-of-Principle Detonation Driven, Linear Electric Generator Facility  

E-print Network

increases with the compression ratio, so a heat exchanger is usually built into the compres- sor system o Overall efficiency Density Subscripts 0 Initial det Post-detonation gas property I. Introduction COMBUSTION via detonation releases the chemical energy of a reactive mixture with higher efficiency compared

Texas at Arlington, University of

336

Equation of State for Gaseous Products of Detonation  

Microsoft Academic Search

There have been many equations of state (EOS) proposed for gaseous products of detonation, from simple theoretically-based EOS to empirically-based EOS with many adjustable parameters. How well these EOS approximate the real behavior depends on the material which is detonated. Gases, for example, are much easier to represent simply than are condensed or solid materials. If we concentrate solely on

Maria Rightley

1998-01-01

337

Conditions of Experimental Realization of an Electric Detonation  

NASA Astrophysics Data System (ADS)

The detonation can be subdivided on chemical one, light one (laser breakdown of gases), electronic one (electric breakdown in solid dielectric from the anode) depending on an energy source. The electric detonation is the chemical detonation with additional energy release in a chemical reaction zone as result of heating from the going electric current. The chemical reaction zone has some thickness and appreciable conductivity. The required effect of an expected electric detonation can be the increase of detonation velocity D related to dimensionless ratio: (D2/D1)^2˜W2/W1. W1 is a density of the released chemical energy (J/m^3), W2 is total density chemical and thermal energy by an external electric source allocated in chemical reaction zone (J/m^3). The pulse electric source should provide density of a flow and specific allocation of energy, corresponding to similar quantities of the chemical nature in a zone of chemical reaction. We analyzed a detonation of disk-shaped assemblage with diameter 20 cm and weight of HE charge about 0,5 kg. The analysis has shown, that the pulse source is necessary for guaranteed realization of an electric detonation with an energy capacity 5 MJ and which can make a current from 0,4 up to 13 MA on prospective load 0,016-0,16 Ohm. We have accepted efficiency of energy transfer at level of 50 percent. The effect of increase of a detonation velocity can make 15-30 percent.

Yankovskiy, Boris

2011-06-01

338

Experimental study on liquid-fueled pulse detonation engine  

Microsoft Academic Search

The research project on pulse detonation engines has been launched in the Key- Laboratory of High Temperature Gas Dynamics of Institute of Mechanics, Chinese Academy of Sciences, since 2000. The recent progress on the research project is introduced in this paper with a special emphasis on the experiment on the liquid-fueled pulse detonation engine model. To gain basic understanding on

Q. H. Mu; C. Wang; W. Zhao; Z. Jiang

2005-01-01

339

Tailored Fuel Injection for Pulsed Detonation Engines via Feedback Control  

Microsoft Academic Search

An architecture is developed for feedback regulation of liquid volume fraction proé les in an air jet coné ned in a tube. The application to the controlled injection of fuel in detonation tubes for pulsed detonation engines is considered.Thearchitectureconsistsoflaserattenuationsensing ofliquidvolumefractionalongthetube,actuation on the liquid injection pressure through an array of solenoidal valves, and proportional- integral feedback. The architecture is validated by

Alberto Aliseda; Kartik B. Ariyur; Olivier Sarrazin; Juan C. Lasheras; Miroslav Krstic

2003-01-01

340

The Fluid Dynamics of an Idealized Pulsed Detonation Engine  

Microsoft Academic Search

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. In this talk, detailed numerical simulations are used to examine the basic fluid dynamics of an idealized pulsed detonation engine. The simulated engine consists of a tube closed at one-end and open at the other. It is shown

K. Kailasanath; G. Patnaik

2000-01-01

341

Analysis of a Pulsed Detonation Thermal Spray Applicator  

Microsoft Academic Search

Pulsed detonation thermal spray applicators are used to deposit particulate-based coatings on metal components. The coatings usually consist of a unique class of thermal spray materials that are widely employed in numerous industries to enhance the surface of metal components. This paper presents an analysis and numerical simulation of an open tube pulsed detonation thermal spray applicator. Calculations are made

MOHAMMAD K. ALKAM; P. BARRY BUTLER

2000-01-01

342

A Numerical and Analytical Study of Detonation Diffraction  

E-print Network

A Numerical and Analytical Study of Detonation Diffraction Thesis by Marco Arienti In Partial Abstract An investigation of detonation diffraction through an abrupt area change has been car- ried out diffraction is closely related to the occurrence of localized re-initiation mechanisms, and is relevant

Barr, Al

343

Jaguar Procedures for Detonation Behavior of Explosives Containing Boron  

NASA Astrophysics Data System (ADS)

The Jaguar product library was expanded to include boron and boron containing products by analysis of Available Hugoniot and static volumetric data to obtain constants of the Murnaghan relationships for the components. Experimental melting points were also utilized to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX—boron mixtures calculated with these relationships using Jaguar are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that the boron does not react near the detonation front or that boron mixtures exhibit eigenvalue detonation behavior (as shown by some aluminized explosives), with higher detonation velocities at the initial points. Analyses of calorimetric measurements for RDX—boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the detonation properties of the formulation.

Stiel, L. I.; Baker, E. L.; Capellos, C.

2009-12-01

344

On the Initiation Mechanism in Exploding Bridgewire and Laser Detonators  

NASA Astrophysics Data System (ADS)

Since its invention by Los Alamos during the Manhattan Project era the exploding bridgewire detonator (EBW) has seen tremendous use and study. Recent development of a laser-powered device with detonation properties similar to an EBW is reviving interest in the basic physics of the deflagration-to-detonation (DDT) process in both of these devices. Cutback experiments using both laser interferometry and streak camera observations are providing new insight into the initiation mechanism in EBWs. These measurements are being correlated to a DDT model of compaction to detonation and shock to detonation developed previously by Xu and Stewart. The DDT model is incorporated into a high-resolution, multi-material model code for simulating the complete process. Model formulation and the modeling issues required to describe the test data will be discussed.

Stewart, D. Scott; Thomas, Keith A.; Clarke, S.; Mallett, H.; Martin, E.; Martinez, M.; Munger, A.; Saenz, Juan

2006-07-01

345

SN 2012hn: a tidal detonation event?  

NASA Astrophysics Data System (ADS)

We propose for a 30 kilosecond observation of SN 2102hn, a Ca-rich gap transient. These enigmatic objects, with properties intermediate between those of classical novae and Type Ia supernovae, can be well-explained by tidal detonations of low mass white dwarfs by intermediate mass black holes. In such a case, fall-back accretion of the tidal debris would power an X-ray source for which we propose to search. Because supermassive black holes will swallow white dwarfs whole, a successful outcome to this proposal would both explain the Ca-rich gap transients *and* establish the existence of intermediate mass black holes.

Maccarone, Thomas

2013-09-01

346

Equation of state for detonation products  

SciTech Connect

To be useful, an equation of state for detonation products must allow rapid computation. The constraints applied by this requirement have surprising thermodynamic effects. Some of these are discussed here. A simple, complete equation of state is proposed, and its properties are discussed. With the form assumed here, all the useful integrals (except for the Riemann integral) can be written simply and explicitly, so the behavior of the important variables can be easily seen. The complete equation of state is calibrated for PBX9404 and PBX9501.

Davis, W.C.

1998-12-31

347

Detailed features of one-dimensional detonations  

NASA Astrophysics Data System (ADS)

The oscillation mechanism and reignition process of one-dimensional unsteady detonations are numerically studied using a one-step chemical reaction model governed by Arrhenius kinetics. A series of simulations, without perturbations from the outflow boundary to the detonation front, are carried out while the degree of overdrive, f, is varied between 1.10 and 1.74 (f=D2/DCJ2; where D is detonation velocity). Shock pressure histories and x-t diagrams are utilized in order to attain precise understanding of the one-dimensional unsteady detonations. At higher degrees of overdrive, f=1.40-1.74, shock pressure histories agree with those of previous studies. The oscillation mechanism is the same as that of the large-disturbance regime of unsteady shock-induced combustion around a projectile. At lower degrees of overdrive, f<1.30, grid resolution affects the eventual results, because half reaction time in the shock pressure exhibits considerable variation. Four typical kinds of oscillation pattern are discussed and are explained by their x-t diagrams and shock pressure histories. Each oscillation mechanism is essentially the same as that of the large-disturbance regime. The reignition process in the failed regime was numerically investigated at f=1.01-1.25. The reignition points tend to converge on a specified point in study of grid refinement, although the oscillation of the shock pressure histories becomes chaotic, suggesting the existence of a unique solution for reignition. All the simulation results for f=1.01-1.20 show the failed regime after initial disturbance at the early stage. The failed regime is compared with the solution of the Riemann problem, and analysis consisting of a Rayleigh line for weak leading shock and a partially burnt Hugoniot curve is adopted. Analysis suggests the concept of partial chemical heat release, indicating the possibility of discontinuous change in conditions, and, indeed, simulation indicates occurrence of explosion. The explosion time derived from the analysis agrees well with the results of simulation.

Daimon, Yu; Matsuo, Akiko

2003-01-01

348

Simulations of pulsating one-dimensional detonations with true fifth order accuracy  

SciTech Connect

A novel, highly accurate numerical scheme based on shock-fitting coupled with fifth order spatial and temporal discretizations is applied to a classical unsteady detonation problem to generate solutions with unprecedented accuracy. The one-dimensional reactive Euler equations for a calorically perfect mixture of ideal gases whose reaction is described by single-step irreversible Arrhenius kinetics are solved in a series of calculations in which the activation energy is varied. In contrast with nearly all known simulations of this problem, which converge at a rate no greater than first order as the spatial and temporal grid is refined, the present method is shown to converge at a rate consistent with the fifth order accuracy of the spatial and temporal discretization schemes. This high accuracy enables more precise verification of known results and prediction of heretofore unknown phenomena. To five significant figures, the scheme faithfully recovers the stability boundary, growth rates, and wave-numbers predicted by an independent linear stability theory in the stable and weakly unstable regime. As the activation energy is increased, a series of period-doubling events are predicted, and the system undergoes a transition to chaos. Consistent with general theories of non-linear dynamics, the bifurcation points are seen to converge at a rate for which the Feigenbaum constant is 4.66 {+-} 0.09, in close agreement with the true value of 4.669201... As activation energy is increased further, domains are identified in which the system undergoes a transition from a chaotic state back to one whose limit cycles are characterized by a small number of non-linear oscillatory modes. This result is consistent with behavior of other non-linear dynamical systems, but not typically considered in detonation dynamics. The period and average detonation velocity are calculated for a variety of asymptotically stable limit cycles. The average velocity for such pulsating detonations is found to be slightly greater than the Chapman-Jouguet velocity.

Henrick, Andrew K. [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States)]. E-mail: ahenrick@nd.edu; Aslam, Tariq D. [Dynamic Experimentation Division, Los Alamos National Laboratory, Group DX-2, MS P952, Los Alamos, NM 87545 (United States)]. E-mail: aslam@lanl.gov; Powers, Joseph M. [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556 (United States)]. E-mail: powers@nd.edu

2006-03-20

349

First-Principles Investigation of Reactive Molecular Dynamics in Detonating Rdx and Tatb  

NASA Astrophysics Data System (ADS)

Possible initial chemical reactions in detonating RDX and TATB that result from intermolecular collisions behind the shock wave front have been investigated using first-principles reactive molecular dynamics. The reaction dynamics was studied as a function of collision velocities and crystallographic orientations. Threshold collision velocities of chemical initiation and products of decomposition were obtained for each orientation, and compared to calculated bond dissociation energies to rationalize the outcome chemical events. Reaction timescales were also determined and used to understand whether these initial chemical events are largely driven by reaction dynamics or temperature.

Oleynik, I. I.; Landerville, A. C.; White, C. T.

2009-12-01

350

Prompt Reaction of Aluminum in Detonating Explosives  

NASA Astrophysics Data System (ADS)

The potential of aluminum reaction to boost detonation energy has been studied for decades, most recently spurred by the availability of nanometer-sized particles. A review of the literature provides perspective for a recent study with the small-scale shock reactivity test. In this test, <1/2-g samples in confinement are shock loaded on one end, and the output at the other end dents a soft witness block. One test series had 0.3 g of HMX mixed with various forms of aluminum added in amounts of up to 25% of the total sample mass, with the deepest dent for H-5 aluminum occuring at 15%. Test results on ammonium perchlorate mixed with H-5 aluminum were consistent with the peak in detonation velocity reported in Combustion and Flame by Price in 1973 on similar mixtures. One outcome of this study is a new interpretation for the participation of aluminum in large scale gap tests on plastic-bonded explosives, which was discussed by Bernecker at this meeting in 1987.

Sandusky, Harold

2005-07-01

351

Bonfire-safe low-voltage detonator  

DOEpatents

A column of explosive in a low-voltage detonator which makes it bonfire-safe includes a first layer of an explosive charge of CP, or a primary explosive, and a second layer of a secondary organic explosive charge, such as PETN, which has a degradation temperature lower than the autoignition temperature of the CP or primary explosives. The first layer is composed of a pair of increments disposed in a bore of a housing of the detonator in an ignition region of the explosive column and adjacent to and in contact with an electrical ignition device at one end of the bore. The second layer is composed of a plurality of increments disposed in the housing bore in a transition region of the explosive column next to and in contact with the first layer on a side opposite from the ignition device. The first layer is loaded under a sufficient high pressure, 25 to 40 kpsi, to achieve ignition, whereas the second layer is loaded under a sufficient low pressure, about 10 kpsi, to allow occurrence of DDT. Each increment of the first and second layers has an axial length-to-diameter ratio of one-half.

Lieberman, Morton L. (Albuquerque, NM)

1990-01-01

352

Bonfire-safe low-voltage detonator  

DOEpatents

A column of explosive in a low-voltage detonator which makes it bonfire-safe includes a first layer of an explosive charge of CP, or a primary explosive, and a second layer of a secondary organic explosive charge, such as PETN, which has a degradation temperature lower than the autoignition temperature of the CP or primary explosives. The first layer is composed of a pair of increments disposed in a bore of a housing of the detonator in an ignition region of the explosive column and adjacent to and in contact with an electrical ignition device at one end of the bore. The second layer is composed of a plurality of increments disposed in the housing bore in a transition region of the explosive column next to and in contact with the first layer on a side opposite from the ignition device. The first layer is loaded under a sufficient high pressure, 25 to 40 kpsi, to achieve ignition, whereas the second layer is loaded under a sufficient low pressure, about 10 kpsi, to allow occurrence of DDT. Each increment of the first and second layers has an axial length-to-diameter ratio of one-half. 2 figs.

Lieberman, M.L.

1988-07-01

353

Detonation synthesis of nanosized titanium dioxide powders  

NASA Astrophysics Data System (ADS)

Utilizing titanyl sulfate as a TiO2 source, via a novel synthesis method—the detonation method—nanosized TiO2(n-TiO2) powders were prepared. The results showed that the as-prepared n-TiO2 powders did not have enough time to grow into large and fine crystallites, and that the characteristics of high temperature, high pressure and high cooling were helpful in the synthesis of nanosized materials. The anatase phase appeared to be the stable form of nanocrystalline TiO2 at small crystallite sizes to some extent and part of the rutile phase could transform to the anatase phase when the detonation products were oxidized to eliminate the impurities via the combined action of chromic anhydride (CrO3) and concentrated nitric acid. The main reason resulting in the reversal of stability of anatase and rutile could be the differences in the surface energy of anatase and rutile at small crystallite sizes.

Qu, Yandong; Li, Xiaojie; Wang, Xiaohong; Liu, Dahui

2007-05-01

354

Unique passive diagnostic for slapper detonators  

NASA Technical Reports Server (NTRS)

The objective of this study was to find a material and configuration that could reliably detect the proper functioning of a slapper (non-explosive) detonator. Because of the small size of the slapper geometry (on the order of a 15 mils), most diagnostic techniques are not suitable. This program has the additional requirements that the device would be used on centrifuge so that it could not use any electrical power or output signals. This required that the diagnostic be completely passive. The paper describes the three facets of the development effort: complete characterization of the slapper using VISAR measurements, selection of the diagnostic material and configuration, and testing of the prototype designs. The VISAR testing required that use of a special optical probe to allow the laser light to reach both bridges of the dual-slapper detonator. Results are given in the form of flyer velocity as a function of the initiating charge voltage level. The selected diagnostic design functions in a manner similar to a dent block except that the impact of the Kapton disk from a properly-functioning slapper causes a fracture pattern. A quick visual inspection is all that is needed to determine if the flyer velocity exceeded the threshold value. Sub-threshold velocities produce a substantially different appearance.

Brigham, William P.; Schwartz, John J.

1994-01-01

355

Legal considerations in a nuclear detonation.  

PubMed

This article summarizes public health legal issues that need to be considered in preparing for and responding to nuclear detonation. Laws at the federal, state, territorial, local, tribal, and community levels can have a significant impact on the response to an emergency involving a nuclear detonation and the allocation of scarce resources for affected populations. An understanding of the breadth of these laws, the application of federal, state, and local law, and how each may change in an emergency, is critical to an effective response. Laws can vary from 1 geographic area to the next and may vary in an emergency, affording waivers or other extraordinary actions under federal, state, or local emergency powers. Public health legal requirements that are commonly of concern and should be examined for flexibility, reciprocity, and emergency exceptions include liability protections for providers; licensing and credentialing of providers; consent and privacy protections for patients; occupational safety and employment protections for providers; procedures for obtaining and distributing medical countermeasures and supplies; property use, condemnation, and protection; restrictions on movement of individuals in an emergency area; law enforcement; and reimbursement for care. PMID:21402813

Sherman, Susan E

2011-03-01

356

Spark-safe low-voltage detonator  

DOEpatents

A column of explosive in a low-voltage detonator which makes it spark-safe ncludes an organic secondary explosive charge of HMX in the form of a thin pad disposed in a bore of a housing of the detonator in an ignition region of the explosive column and adjacent to an electrical ignition device at one end of the bore. The pad of secondary charge has an axial thickness within the range of twenty to thirty percent of its diameter. The explosive column also includes a first explosive charge of CP disposed in the housing bore in the ignition region of the explosive column next to the secondary charge pad on a side opposite from the ignition device. The first CP charge is loaded under sufficient pressure, 25 to 40 kpsi, to provide mechanical confinement of the pad of secondary charge and physical coupling thereof with the ignition device. The explosive column further includes a second explosive charge of CP disposed in the housing bore in a transition region of the explosive column next to the first CP charge on a side opposite from the pad of secondary charge. The second CP charge is loaded under sufficient pressure, about 10 kpsi, to allow occurrence of DDT. The first explosive CP charge has an axial thickness within the range of twenty to thirty percent of its diameter, whereas the second explosive CP charge contains a series of increments (nominally 4) each of which has an axial thickness-to-diameter ratio of one to two.

Lieberman, Morton L. (Albuquerque, NM)

1989-01-01

357

Injection and Mixing of Gas Propellants for Pulse DetonationPropulsion  

E-print Network

Injection and Mixing of Gas Propellants for Pulse DetonationPropulsion Dora Elia Musielak Detonation has received attention of late because of its role as the primary combustion mechanism in rocket utilization of detonation combustion in these applications. The detonation process has been studied

Texas at Arlington, University of

358

American Institute of Aeronautics and Astronautics Experimental Study on Deflagration-to-Detonation  

E-print Network

with pulsed detonation operations provided appropriate preventive measures were taken. One of the major into a moderate-frequency pulsed detonation engine system as well as the effectiveness of the deflagration and the impact on pulse detonation operations are highlighted. I. Introduction ULSE detonation engines have been

Texas at Arlington, University of

359

Investigation of instabilities affecting detonations: Improving the resolution using block-structured adaptive mesh refinement  

NASA Astrophysics Data System (ADS)

The unstable nature of detonation waves is a result of the critical relationship between the hydrodynamic shock and the chemical reactions sustaining the shock. A perturbative analysis of the critical point is quite challenging due to the multiple spatio-temporal scales involved along with the non-linear nature of the shock-reaction mechanism. The author's research attempts to provide detailed resolution of the instabilities at the shock front. Another key aspect of the present research is to develop an understanding of the causality between the non-linear dynamics of the front and the eventual breakdown of the sub-structures. An accurate numerical simulation of detonation waves requires a very efficient solution of the Euler equations in conservation form with detailed, non-equilibrium chemistry. The difference in the flow and reaction length scales results in very stiff source terms, requiring the problem to be solved with adaptive mesh refinement. For this purpose, Berger-Colella's block-structured adaptive mesh refinement (AMR) strategy has been developed and applied to time-explicit finite volume methods. The block-structured technique uses a hierarchy of parent-child sub-grids, integrated recursively over time. One novel approach to partition the problem within a large supercomputer was the use of modified Peano-Hilbert space filling curves. The AMR framework was merged with CLAWPACK, a package providing finite volume numerical methods tailored for wave-propagation problems. The stiffness problem is bypassed by using a 1st order Godunov or a 2nd order Strang splitting technique, where the flow variables and source terms are integrated independently. A linearly explicit fourth-order Runge-Kutta integrator is used for the flow, and an ODE solver was used to overcome the numerical stiffness. Second-order spatial resolution is obtained by using a second-order Roe-HLL scheme with the inclusion of numerical viscosity to stabilize the solution near the discontinuity. The scheme is made monotonic by coupling the van Albada limiter with the higher order MUSCL-Hancock extrapolation to the primitive variables of the Euler equations. Simulations using simplified single-step and detailed chemical kinetics have been provided. In detonations with simplified chemistry, the one-dimensional longitudinal instabilities have been simulated, and a mechanism forcing the collapse of the period-doubling modes was identified. The transverse instabilities were simulated for a 2D detonation, and the corresponding transverse wave was shown to be unstable with a periodic normal mode. Also, a Floquet analysis was carried out with the three-dimensional inviscid Euler equations for a longitudinally stable case. Using domain decomposition to identify the global eigenfunctions corresponding to the two least stable eigenvalues, it was found that the bifurcation of limit cycles in three dimensions follows a period doubling process similar to that proven to occur in one dimension and it is because of transverse instabilities. For detonations with detailed chemistry, the one dimensional simulations for two cases were presented and validated with experimental results. The 2D simulation shows the re-initiation of the triple point leading to the formation of cellular structure of the detonation wave. Some of the important features in the front were identified and explained.

Ravindran, Prashaanth

360

Recent papers from DX-1, detonation science and technology  

SciTech Connect

Over the past year members of DX-1 have participated in several conferences where presentations were made and papers prepared for proceedings. There have also been several papers published in or submitted to refereed journals for publication. Rather that attach all these papers to the DX-1 Quarterly Report, we decided to put them in a Los Alamos report that could be distributed to those who get the quarterly, as well as others that have an interest in the work being done in DX-1 both inside and outside the Laboratory. This compilation does not represent all the work reported during the year because some people have chosen not to include their work here. In particular, there were a number of papers relating to deflagration-to-detonation modeling that were not included. However, this group of papers does present a good picture of much of the unclassified work being done in DX-1. Several of the papers include coauthors from other groups or divisions at the Laboratory, providing an indication of the collaborations in which people in DX-1 are involved. Discussed topics of submitted papers include: shock compression of condensed matter, pyrotechnics, shock waves, molecular spectroscopy, sound speed measurements in PBX-9501, chemical dimerization, and micromechanics of spall and damage in tantalum.

NONE

1996-10-01

361

On the Initiation Mechanism in Exploding Bridgewire and Laser Detonators  

NASA Astrophysics Data System (ADS)

Since its invention by Los Alamos during the Manhattan Project era the exploding bridgewire detonator (EBW) has seen tremendous use and study. Recent development of a laser-powered device with detonation properties similar to an EBW is reviving interest in the basic physics of the Deflagration-to-Detonation (DDT) process in both of these devices,[1]. Cutback experiments using both laser interferometry and streak camera observations are providing new insight into the initiation mechanism in EBWs. These measurements are being correlated to a DDT model of compaction to detonation and shock to detonation developed previously by Xu and Stewart, [2]. The DDT model is incorporated into a high-resolution, multi-material model code for simulating the complete process. Model formulation and predictions against the test data will be discussed. REFS. [1] A. Munger, J. Kennedy, A. Akinci, and K. Thomas, "Dev. of a Laser Detonator" 30th Int. Pyrotechnics Seminar, Fort Collins, CO, (2004). [2] Xu, S. and Stewart, D. S. Deflagration to detonation transition in porous energetic materials: A model study. J. Eng. Math., 31, 143-172 (1997)

Stewart, D. Scott; Thomas, K.; Saenz, J.

2005-07-01

362

Unsteady thrust measurement techniques for pulse detonation engines  

NASA Astrophysics Data System (ADS)

Thrust is a critical performance parameter and its correct determination is necessary to characterize an engine. Many conventional thrust measurement techniques prevail. However, further developments are required for correct measurement of thrust in the case of a pulse detonation engine (PDE), since the entire thrust generation process is intermittent. The significant effect of system dynamics in the form of inertial forces, stress wave propagation and reflections initiated in the structure due to detonations and pulse-to-pulse interaction in a fast operating PDE further complicate the thrust measurement process. These complications call for a further, detailed study of the unsteady thrust characteristics. A general approach was first developed to recover actual thrust from the measured thrust generated by the PDE. The developed approach consisted of two steps. The first step incorporated a deconvolution procedure using a pre-established system transfer function and measured input to reconstruct the output yielding the deconvolved thrust. The second step accounted for inertial forces through an acceleration compensation procedure. These two steps allowed the actual thrust to be determined. A small scale PDE operating at 10 and 20 Hz with varied filling fractions and mixture equivalence ratios was used for the experimental application of the general approach. The analytical study of gas dynamics in the PDE while in operation and the measured pressure histories at the exit of the engine allowed the generated thrust during a cycle to be determined semi-empirically. The thrust values determined semi-empirically were compared against the experimental results. A dynamical model of the PDE was created for the study of the unsteady thrust characteristics using finite element analysis. The results from finite element analysis were compared against semi-empirical and experimental results. In addition, finite element analysis also facilitated to numerically determine the unsteady thrust generated by the PDE at higher operating frequencies of 50 and 100 Hz. The actual thrust estimated experimentally, semi-empirically and numerically were expressed in the form of specific impulse for comparison. The results obtained via semi-empirical method and finite element analysis were found to be in good agreement with each other. However, the results obtained experimentally were slightly lower than the other two. Finally, the results obtained in this research work were also compared against the findings reported in literature. The comparison gave satisfying results. The developed general approach used to recover actual thrust generated by a PDE was also used to recover actual aerodynamic drag experienced by a blunt nose cone model in a nominal Mach 8-9 flow. The limited validation against modified Newtonian theory was provided as the results obtained after applying the developed approach matched the predicted values.

Joshi, Dibesh Dhoj

363

A boundary-layer treatment for turbulent detonation waves  

NASA Technical Reports Server (NTRS)

The profile of turbulent intensity versus Reynolds number from bursts found in an ignition front agrees with the Orr-Sommerfeld solutions for unstable boundary-layer flow. This result provides the first evidence of a formal connection between bursting transition to turbulence in flows which share the boundary-layer approximation but which are otherwise unrelated.

Johnson, J. A., III

1980-01-01

364

Nearly spherical constant power detonation waves driven by focused radiation  

NASA Technical Reports Server (NTRS)

Shape and inner flow of a tridimensional spark are studied. The spark is created by focusing a laser beam in a gas. A second order fully non-linear equation is derived for the radial velocity on the axis of symmetry in the neighborhood of the origin. Solutions to that equation display the existence of a forbidden region near the focus, thus indicating the limits of applicability of a small perturbation solution.

George, Y. H.

1973-01-01

365

High Order Hybrid Numerical Simulations of Two Dimensional Detonation Waves  

E-print Network

-called "triple points" which have three shock configurations [4] (an incident shock, a reflected shock and a Mach = pressure Q = specific heat formation s = entropy t = time t = tangential direction of shock front of experimentalists trying to measure the cell size of the cellular pattern [5]. In this paper, we will present a high

Cai, Wei

366

Dynamic pressure measurement of shock waves in explosives by means of a fiber Bragg grating sensor  

Microsoft Academic Search

A new technique for the dynamic measurement of detonation pressures by use of a Fibre Bragg Grating (FBG) sensor is reported. A variation in pressure changes the wavelength of the FBG reflected light. In a detonation, the shock wave passes the explosive with a velocity of ca. 7 km\\/s and the pressure builds up to ca. 20 GPa within 100

P. G. van't Hof; L. K. Cheng; J. H. G. Scholtes; W. C. Prinse

2007-01-01

367

Dynamic pressure measurement of shock waves in explosives by means of a fiber Bragg grating sensor  

Microsoft Academic Search

A new technique for the dynamic measurement of detonation pressures by use of a Fibre Bragg Grating (FBG) sensor is reported. A variation in pressure changes the wavelength of the FBG reflected light. In a detonation, the shock wave passes the explosive with a velocity of ca. 7 km\\/s and the pressure builds up to ca. 20 GPa within 100

L. K. Cheng; W. C. Prinse

368

Theoretical solution of the minimum charge problem for gaseous detonations  

SciTech Connect

A theoretical model was developed for the minimum charge to trigger a gaseous detonation in spherical geometry as a generalization of the Zeldovich model. Careful comparisons were made between the theoretical predictions and experimental data on the minimum charge to trigger detonations in propane-air mixtures. The predictions are an order of magnitude too high, and there is no apparent resolution to the discrepancy. A dynamic model, which takes into account the experimentally observed oscillations in the detonation zone, may be necessary for reliable predictions. 27 refs., 9 figs.

Ostensen, R.W.

1990-12-01

369

Theoretical analysis of a rotating two-phase detonation in liquid rocket motors.  

NASA Technical Reports Server (NTRS)

A nonlinear analysis to study tangential mode shock instabilities in a thin annular chamber is carried out by employing a one dimensional two phase detonation wave as a reaction model. It is assumed that phase change and reaction take place only within the wave, which is treated as a discontinuity. The annulus is unrolled and the flow is considered as two dimensional with the coordinate system fixed on the wave front. Between waves, the flow is assumed to be isentropic with no interaction between droplets and burned gases. Jump conditions across the wave are solved for two phase flow. The average pressure along the injection plate is related to the design chamber pressure by the use of overall conservation equations. The wave strength is written in terms of the design parameters of the chamber. The results compare favorably with existing experiments. Finally, the effects of drop size on the wave strength are discussed and a simple criterion which sets the lower limit of validity for this strong wave analysis, is presented.

Shen, P. I.-W.; Adamson, T. C., Jr.

1972-01-01

370

Analysis of pulse detonation turbojet engines  

NASA Astrophysics Data System (ADS)

Research over the last two decades has shown the potential advantages of pulse detonation engines (PDEs) over existing aero-engines in terms of improved thermodynamics efficiency, improved thrust performance, simplicity of design, and flexibility to operate over a wide speed range. The inherently unsteady characteristic of PDEs makes it difficulty to analyze and evaluate their performance. The conventional method that relies on steady-state assumptions cannot be directly applied. PDE studies have to employ unsteady gasdynamics behavior. In this study, the thermodynamic cycle of a PDE, which can be called the ZND cycle, is theoretically analyzed. A parametric analysis of turbojet PDEs is considered for both ideal and non-ideal cases. The conventional turbojet with a Brayton cycle is brought in the comparison to verify that PDEs can provide better performance.

Vutthivithayarak, Ronnachai

2011-12-01

371

The dynamics of unsteady detonation with diffusion  

SciTech Connect

Here we consider an unsteady detonation with diffusion included. This introduces an interaction between the reaction length scales and diffusion length scales. Detailed kinetics introduce multiple length scales as shown though the spatial eigenvalue analysis of hydrogen-oxygen system; the smallest length scale is {approx} 10{sup 7} m and the largest {approx} 10{sup -2} m; away from equilibrium, the breadth can be larger. In this paper, we consider a simpler set of model equations, similar to the inviscid reactive compressible fluid equations, but include diffusion (in the form of thermal/energy, momentum, and mass diffusion). We will seek to reveal how the complex dynamics already discovered in one-step systems in the inviscid limit changes with the addition of diffusion.

Aslam, Tariq Dennis [Los Alamos National Laboratory; Romick, Christopher [NOTRE DAME; Powers, Joseph [NOTRE DAME

2010-01-01

372

Equation of state for detonation products  

SciTech Connect

An equation of state for detonation products, with the usual form p = p(v,E), is proposed. It allows independent calibration of the adiabatic gamma and the Grueneisen gamma, and gives them forms in agreement with recent theoretical studies. The equation of state is given by p = E/v[k {minus} 1 + F(v) {l_brace}1 + b(1 {minus} E/E{sup s}(v)){r_brace}] where F(v) drops from a finite value at small v to zero at large v, b is a constant, and E{sup s}(v) is the specific internal energy on the principal isentrope. Its relationship to the polytropic gas equation of state p = (E/v)({gamma} {minus} 1) is easily seen, and it reduces to this form at large volume.

Davis, W.C.

1993-05-01

373

Spark-safe low-voltage detonator  

DOEpatents

A column of explosive in a low-voltage detonator which makes it spark-safe includes an organic secondary explosive charge of HMX in the form of a thin pad disposed in a bore of a housing of the detonator in an ignition region of the explosive column and adjacent to an electrical ignition device at one end of the bore. The pad of secondary charge has an axial thickness within the range of twenty to thirty percent of its diameter. The explosive column also includes a first explosive charge of CP disposed in the housing bore in the ignition region of the explosive column next to the secondary charge pad on a side opposite from the ignition device. The first CP charge is loaded under sufficient pressure, 25 to 40 kpsi, to provide mechanical confinement of the pad of secondary charge and physical coupling thereof with the ignition device. The explosive column further includes a second explosive charge of CP disposed in the housing bore in a transition region of the explosive column next to the first CP charge on a side opposite from the pad of secondary charge. The second CP charge is loaded under sufficient pressure, about 10 kpsi, to allow occurrence of DDT. The first explosive CP charge has an axial thickness within the range of twenty to thirty percent of its diameter, whereas the second explosive CP charge contains a series of increments (nominally 4), each of which has an axial thickness-to-diameter ratio of one to two. 2 figs.

Lieberman, M.L.

1988-07-01

374

Jaguar Analyses of Experimental Detonation Values for Aluminized Explosives  

NASA Astrophysics Data System (ADS)

Comparisons of JAGUAR C-J velocities with experimental detonation values for a number of explosives indicate that only slight, if any, aluminum reaction occurs at the detonation front even if small or sub-micron particles are utilized. For sub-micron particles, it is important to account for the presence of aluminum oxide in the explosive formulation. The agreement with the calculated JAGUAR values for zero aluminum reaction is within 2% for most experimental detonation velocities considered. Comparisons of experimental cylinder velocities by JAGUAR analytical procedures indicate that with small aluminum particles substantial aluminum reaction occurs at low values of the radial expansion, even though little reaction is observed at the detonation front.

Stiel, Leonard I.; Baker, Ernest L.; Capellos, Christos

2004-07-01

375

Ultrafast Detonation of Hydrazoic Acid (HN[subscript 3])  

E-print Network

The fastest self-sustained chemical reactions in nature occur during detonation of energetic materials where reactions are thought to occur on nanosecond or longer time scales in carbon-containing materials. Here we perform ...

Rodriguez, Alejandro W.

376

Level-Set Techniques Applied to Unsteady Detonation Propagation  

E-print Network

Level-Set Techniques Applied to Unsteady Detonation Propagation D. Scott Stewart1 Tariq Aslam1 Jin. Examples include #12;2 D. Scott Stewart Tariq Aslam Jin Yao and John B. Bdzil solidification and the Stefan

Aslam, Tariq

377

LevelSet Techniques Applied to Unsteady Detonation Propagation  

E-print Network

## Level­Set Techniques Applied to Unsteady Detonation Propagation D. Scott Stewart 1 Tariq Aslam 1 #12; 2 D. Scott Stewart Tariq Aslam Jin Yao and John B. Bdzil solidification and the Stefan problem

Aslam, Tariq

378

[Detonation temperature measurement of epoxypropane using instantaneous spectrum method].  

PubMed

After solving the problems of synchronization of the measuring system and the avoidance of false trigger signal, the instantaneous emission spectrum of epoxypropane with an exposure time of 2 micros and a resolution of 0.2 nm was acquired from a side window of a shock tube at the very moment when the epoxypropane transformed from deflagration to detonation. The measuring system consists of an advanced intensified charge-coupled-device spectroscopic detector, a digital delay generator DG535, an explosion shock tube and optical fibers. The DDT process was monitored by pressure transducers. After correcting the intensity of the spectrum obtained, the background curve of the heat radiation intensity of the detonation was given immediately. The detonation temperature of 2 416 K for epoxypropane was derived from fitting the curve with Planck blackbody formula by least squares principle. The detonation temperature of epoxypropane can provide an experimental datum for analyzing the microscopic mechanism of DDT process. PMID:18536396

Li, Ying; Li, Ping; Xiao, Hai-Bo; Hu, Dong; Yuan, Chang-Ying

2008-03-01

379

Quasi-One-Dimensional Modeling of Pulse Detonation Rocket Engines  

NASA Technical Reports Server (NTRS)

This viewgraph presentation provides information on the engine cycle of a pulse detonation rocket engine (PDRE), models for optimizing the performance of a PDRE, and the performance of PDREs in comparison to Solid State Rocket Engines (SSREs).

Morris, Christopher I.

2003-01-01

380

An experimental study of laser-supported plasmas for laser propulsion: Center director's discretionary fund project DFP-82-33  

NASA Technical Reports Server (NTRS)

The rudiments of a rocket thruster, which receives its enthalpy from an energy source which is remotely beamed from a laser, is described. An experimental study, now partially complete, is discussed which will eventually provide a detailed understanding of the physics for assessing the feasibility of using hydrogen plasmas for accepting and converting this energy to enthalpy. A plasma ignition scheme which uses a pulsed CO2 laser was develped and the properites of the ignition spark documented, including breakdown intensities in hydrogen. A complete diagnostic system capable of determining plasma temperature and the plasma absorptivitiy for subsequent steady-state absorption of a high power CO2 laser beam are developed and demonstrative use is discussed for the preliminary case study, a two atmosphere laser supported argon plasma.

Eskridge, R. H.; Mccay, T. D.; Vanzandt, D. M.

1987-01-01

381

Hypervelocity reactive dynamics in detonating PETN, RDX, and HMX energetic materials  

NASA Astrophysics Data System (ADS)

Despite intensive experimental and theoretical efforts, the first chemical events that trigger the chemistry behind the shock wave front in detonating materials are still largely unknown. We investigate the chemical initiation of detonation in shock compressed PETN, RDX, and HMX which results from intermolecular collisions behind the shock wave using first-principles reactive molecular dynamics. The reaction dynamics of bimolecular collisions were studied as a function of collision velocities and crystallographic orientations. For each orientation, threshold collision velocities of reaction, and products of decomposition were determined. The timescale of reaction was determined and used to understand whether these initial chemical events are largely driven by reaction dynamics, or temperature. Bond dissociation energies were calculated for each molecule and used to rationalize the outcome of the chemical events in the course of the reaction dynamics. A correlation between the order in which products are formed and the relative strengths of the bonds within the bimolecular complexes was investigated. Finally, the relationship between orientation dependent sensitivities and steric factors is discussed.

Landerville, Aaron; Oleynik, Ivan; White, Carter

2009-06-01

382

A Study of Detonation Propagation and Diffraction with Compliant Confinement  

Microsoft Academic Search

A previous computational study of diffracting detonations with the ignition-and-growth model demonstrated that contrary to experimental observations, the computed solution did not exhibit dead zones. For a rigidly confined explosive it was found that while diffraction past a sharp corner did lead to a temporary separation of the lead shock from the reaction zone, the detonation re-established itself in due

J Banks; D Schwendeman; A Kapila; W Henshaw

2007-01-01

383

Air-Breathing Liquid-Fueled Pulse Detonation Engine Demonstrator  

Microsoft Academic Search

For the first time, a demonstrator of a new type of air-breathing liquid-fueled engine—a pulse detonation engine—has been designed and tested. Work on creating a pulse detonation engine is being carried out more and more actively [1, 2]. Such engines operate on a new principle of conversion of the chemical energy of fuel into propulsion, on which fuel is burnt

S. M. Frolov; V. S. Aksenov; V. Ya. Basevich

2005-01-01

384

The Fluid Dynamics of a Pulse Detonation Engine-V  

Microsoft Academic Search

Pulsed Detonation Engines (PDE) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Previously, several aspects of the fluid dynamics of a PDE have been presented at these meetings. Reliable and repeated low-energy initiation of detonations in the high-speed flow in PDEs operating on fuel-air mixtures is one of the remaining

K. Kailasanath; C. Li

2004-01-01

385

The Physics of Deflagration-to-Detonation Transition in Type Ia Supernovae  

NASA Astrophysics Data System (ADS)

BACKGROUND: The scenario currently best capable of explaining the observational properties of normal bright type Ia supernovae (SNIa), which are of primary importance for cosmology, is the delayed detonation model of the explosion of a white dwarf star with the mass near the Chandrasekhar limit in a single-degenerate binary system. In this model, the explosion starts as a subsonic deflagration that later transitions to a supersonic detonation (deflagration-to-detonation transition, or DDT). Significant progress has been made over the years both experimentally and numerically in elucidating the physics of DDT in terrestrial confined systems. It remains unclear, however, whether and how a detonation can be formed in an unpressurized, unconfined system such as the interior of a WD. Modern large-scale multidimensional models of SNIa cannot capture the DDT process and, thus, are forced to make two crucial assumptions, namely (a) that DDT does occur at some point, and (b) when and where it occurs. As a result, delayed detonation is a parameterized model that must be "tuned" in order to obtain the proper match with the observations. This substantially hinders the possibility of investigating potential sources of systematic errors in the calibration of normal bright SNIa as standard candles. Recently we have carried out a systematic study of the high-speed turbulence-flame interaction through first-principles direct numerical simulations (DNS) using reaction models similar to those describing terrestrial chemical flames. Our analysis has shown that at sufficiently high turbulent intensities, subsonic turbulent flames in unconfined environments, such as the WD interior, are indeed inherently susceptible to DDT. The associated mechanism is based on the unsteady evolution of turbulent flames faster than the Chapman-Jouguet deflagrations. This process is qualitatively different from the traditional spontaneous reaction wave model and does not require the formation of distributed flames. These results provide the first direct ab initio demonstration of DDT in turbulent reactive flows. They show that DDT is indeed possible in unconfined media and provide a detailed physical description of this process. OBJECTIVES: Here we propose to perform the detailed and systematic analysis of the new spontaneous DDT mechanism to demonstrate its applicability in SNIa explosions and to determine precise conditions required for the onset of DDT. Culmination of this effort will be the first DNS-validated subgrid-scale DDT model capable of accurately predicting the time and location of detonation initiation and suitable for use in large-scale SNIa simulations. METHODS: All key stages of the new DDT mechanism will be studied using high-resolution direct numerical simulations of turbulence interaction with both chemical and thermonuclear flames. These will be carried out with fixed grid and adaptive mesh refinement numerical codes that have previously been extensively used in studies of both terrestrial and astrophysical combustion. The results will be incorporated as a subgrid model in large-scale 3D fluid dynamics calculations of SNIa. SIGNIFICANCE: Analysis performed in the course of this work will remove the parameterization of the single-degenerate delayed detonation model on DDT conditions. This, in turn, will open the possibility for meaningful comparison of the observational signatures of this explosion scenario with the photometric, spectroscopic, and polarimetric signatures of SNIa and, thus, for identifying and describing potential sources of systematic errors in SNIa calibration as cosmological standard candles. Substantial improvement of the accuracy of such calibration will be crucial for the success of current and future NASA missions aimed at studying the nature of dark energy.

Poludnenko, Alexei

386

Nature of the buildup to detonation in solid high explosives during plane shock initiation. [PBX-9404 and PBX-9502  

SciTech Connect

Two models for the initiation process are compared to results of experimental studies of initiation of detonation in two high explosives, PBX-9404 (HMX-based) and PBX-9502 (TATB-based), by sustained shock waves. A critical examination of the model known as single-curve buildup is made. Several comparisons are made with experimental results for the two explosives. The model describes the observed shock trajectories moderately well although it has some limitations. These are manifested by an examination of the relation between input pressure and distance of run to detonation. The data are also compared with model solutions for the initiation process which assume self-similar flow. The model can fit the experimental shock trajectory reasonably well but difficulties are encountered in attempting to complete the solution for the entire flow field. For PBX-9404, published pressure-time profiles are examined for self-similar character. The measured profiles show substantial disagreement with the similarity model.

Dick, J.J.

1980-01-01

387

Experimental Studies on Detonation Initiation of Liquid-Fuel-Air Mixture in a Pulse Detonation Engine with Initiator  

Microsoft Academic Search

Detonation initiation in a liquid-fuel pulse detonation engine (PDE) was experimentally investigated. The PDE at Hiroshima University consisted of an initiator and a main combustor. The initiator was filled with liquid-fuel-oxygen mixture, and the main combustor was filled with liquid-fuel-air mixture. The experiments were carried out with varying the volume of the initiator and of the injected liquid-fuel-oxygen mixture. It

Tomoaki Yatsufusa; Masahiro Ohira; Shin'Ichi Yamamoto; Kazuhiro Nishimura; Koichi Yoshinaga; Takuma Endo; Shiro Taki

2005-01-01

388

Simulation of the reflected blast wave from a C-4 charge  

NASA Astrophysics Data System (ADS)

The reflection of a blast wave from a C4 charge detonated above a planar surface is simulated with our ALE3D code. We used a finely-resolved, fixed Eulerian 2-D mesh (167 ?m per cell) to capture the detonation of the charge, the blast wave propagation in nitrogen, and its reflection from the surface. The thermodynamic properties of the detonation products and nitrogen were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. Computed pressure histories are compared with pressures measured by Kistler 603B piezoelectric gauges at 7 ranges (GR = 0, 5.08, 10.16, 15.24, 20.32, 25.4, and 30.48 cm) along the reflecting surface. Computed and measured waveforms and positive-phase impulses were similar, except at close-in ranges (GR < 5 cm), which were dominated by jetting effects.

Howard, W. Michael; Kuhl, Allen L.; Tringe, Joseph

2012-03-01

389

Particle Acceleration in a High Enthalpy Nozzle Flow with a Modified Detonation Gun  

NASA Astrophysics Data System (ADS)

The quality of thermal sprayed coatings depends on many factors which have been investigated and are still in scientific focus. Mostly, the coating material is inserted into the spray device as solid powder. The particle condition during the spray process has a strong effect on coating quality. In some cases, higher particle impact energy leads to improved coating quality. Therefore, a computer-controlled detonation gun based spraying device has been designed and tested to obtain particle velocities over 1200 m/s. The device is able to be operated in two modes based on different flow-physical principles. In one mode, the device functions like a conventional detonation gun in which the powder is accelerated in a blast wave. In the other mode, an extension with a nozzle transforms the detonation gun process into an intermittent shock tunnel process in which the particles are accelerated in a high enthalpy nozzle flow with high reservoir conditions. Presented are experimental results of the operation with nozzle in which the device generates very high particle velocities up to a frequency of 5 Hz. A variable particle injection system allows injection of the powder at any point along the nozzle axis to control particle temperature and velocity. A hydrogen/oxygen mixture is used in the experiments. Operation performance and nozzle outflow are characterized by time resolved pressure measurements. The particle conditions inside the nozzle and in the nozzle exit plane are calculated with a quasi-one-dimensional WENO-code of high order. For the experiments, particle velocity is obtained by particle image velocimetry, and particle concentration is qualitatively determined by a laser extinction method. The powders used are WC-Co(88/12), NiCr(80/20), Al2O3, and Cu. Different substrate/powder combinations for varying particle injection positions have been investigated by light microscopy and measurements of microhardness.

Henkes, C.; Olivier, H.

2014-04-01

390

Flowfield characterization and model development in detonation tubes  

NASA Astrophysics Data System (ADS)

A series of experiments and numerical simulations are performed to advance the understanding of flowfield phenomena and impulse generation in detonation tubes. Experiments employing laser-based velocimetry, high-speed schlieren imaging and pressure measurements are used to construct a dataset against which numerical models can be validated. The numerical modeling culminates in the development of a two-dimensional, multi-species, finite-rate-chemistry, parallel, Navier-Stokes solver. The resulting model is specifically designed to assess unsteady, compressible, reacting flowfields, and its utility for studying multidimensional detonation structure is demonstrated. A reduced, quasi-one-dimensional model with source terms accounting for wall losses is also developed for rapid parametric assessment. Using these experimental and numerical tools, two primary objectives are pursued. The first objective is to gain an understanding of how nozzles affect unsteady, detonation flowfields and how they can be designed to maximize impulse in a detonation based propulsion system called a pulse detonation engine. It is shown that unlike conventional, steady-flow propulsion systems where converging-diverging nozzles generate optimal performance, unsteady detonation tube performance during a single-cycle is maximized using purely diverging nozzles. The second objective is to identify the primary underlying mechanisms that cause velocity and pressure measurements to deviate from idealized theory. An investigation of the influence of non-ideal losses including wall heat transfer, friction and condensation leads to the development of improved models that reconcile long-standing discrepancies between predicted and measured detonation tube performance. It is demonstrated for the first time that wall condensation of water vapor in the combustion products can cause significant deviations from ideal theory.

Owens, Zachary Clark

391

Deflagration to detonation experiments in granular HMX  

SciTech Connect

In this paper the authors report on continuing work involving a series of deflagration-to-detonation transition (DDT) experiments in which they study the piston-initiated DDT of heavily confined granular cyclotetramethylenetetranitramine (HMX). These experiments were designed to he useful in model development and evaluation. A main focus of these experiments is the effect of density on the DDT event. Particle size distribution and morphology are carefully characterized. In this paper they present recent surface area analysis. Earlier studies demonstrated extensive fracturing and agglomeration in samples at densities as low as 75% TMD as evidenced by dramatic decreases in particle size distribution due to mild stimulus. This is qualitatively confirmed with SEM images and quantitatively studied with gas absorption surface area analysis. Also, in this paper they present initial results using a microwave interferometer technique. Dynamic calibration of the technique was performed, a 35 GHz signal is used to increase resolution, and the system has been designed to be inexpensive for repeated experiments. The distance to where deformation of the inner wall begins for various densities is reported. This result is compared with the microwave interferometer measurements.

Burnside, N.J.; Son, S.F.; Asay, B.W.; Dickson, P.M.

1998-03-01

392

What is a shock wave to an explosive molecule?*  

NASA Astrophysics Data System (ADS)

To an explosive molecule, a shock wave is a "wake-up call" and a heat source. When a shock wave passes over an explosive molecule, the molecule is compressed, heated, and accelerated in the direction of the shock wave front motion. The acceleration and compression processes require just a few molecular collisions with neighboring explosive molecules, but the excitation processes for the molecule's vibrational degrees of freedom are more complex and require many more collisions. If the shock wave is strong enough to excite one of the metastable explosive molecule's vibrational modes into a reactive transition state, chemical decomposition begins. If the duration of the shock compression is long enough, sufficient exothermic reaction occurs to cause buildup to detonation. For homogeneous explosives (gases, liquids, and perfect solid crystals), after an induction time, this rapid exothermic reaction occurs as a thermal explosion in the explosive molecules first struck by the shock wave. A "superdetonation" wave travels through the shocked explosive until it overtakes the original shock wave and then decreases in velocity until the Chapman-Jouguet (CJ) thermodynamic equilibrium detonation velocity is attained. For heterogeneous liquid and solid explosives, the chemical energy release begins at "hot spots" formed by various mechanical processes (void collapse, friction between particles, shear deformation, etc.) caused by the passage of the original shock wave front. These "hot spots" can grow and thermally ignite the surrounding explosive molecules leading to detonation, or they can lose their heat by thermal diffusion and detonation fails to develop. Self-sustaining detonation waves in all explosives exhibit a complex three-dimensional structure of Mach stem interactions. Current experimental and theoretical understanding of shock initiation and detonation wave propagation are reviewed, and directions for future research are discussed. *This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

Tarver, Craig

2001-06-01

393

The development of laser ignited deflagration-to-detonation transition (DDT) detonators and pyrotechnic actuators  

SciTech Connect

The use of laser ignited explosive components has been recognized as a safety enhancement over existing electrical explosive devices (EEDs). Sandia has been pursuing the development of optical ordnance for many years with recent emphasis on developing optical deflagration-to-detonation (DDT) detonators and pyrotechnic actuators. These low energy optical ordnance devices can be ignited with either a semiconductor diode laser, laser diode arrays or a solid state rod laser. By using a semiconductor laser diode, the safety improvement can be made without sacrificing performance since the input energy required for the laser diode and the explosive output are similar to existing electrical systems. The use of higher powered laser diode arrays or rod lasers may have advantages in fast DDT applications or lossy optical environments such as long fiber applications and applications with numerous optical connectors. Recent results from our continued study of optical ignition of explosive and pyrotechnic materials are presented. These areas of investigation can be separated into three different margin categories: (1) the margin relative to intended inputs (i.e. powder performance as a function of laser input variation), (2) the margin relative to anticipated environments (i.e. powder performance as a function of thermal environment variation), and (3) the margin relative to unintended environments (i.e. responses to abnormal environments or safety).

Merson, J.A.; Salas, F.J.; Harlan, J.G.

1993-11-01

394

33 CFR 154.822 - Detonation arresters, flame arresters, and flame screens.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Detonation arresters, flame arresters, and flame screens. 154.822 Section 154.822 Navigation...Control Systems § 154.822 Detonation arresters, flame arresters, and flame screens. (a) Each...

2010-07-01

395

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Explosives and detonators in underground magazines...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1312 Explosives and detonators in underground...

2012-07-01

396

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Damaged or deteriorated explosives and detonators. 75.1328 Section...STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1328 Damaged or deteriorated explosives and detonators. (a) Damaged...

2011-07-01

397

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Damaged or deteriorated explosives and detonators. 75.1328 Section...STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1328 Damaged or deteriorated explosives and detonators. (a) Damaged...

2010-07-01

398

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Explosives and detonators outside of magazines. 75...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1313 Explosives and detonators outside of magazines....

2013-07-01

399

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Explosives and detonators outside of magazines. 75...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1313 Explosives and detonators outside of magazines....

2012-07-01

400

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Explosives and detonators in underground magazines...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1312 Explosives and detonators in underground...

2014-07-01

401

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Explosives and detonators outside of magazines. 75...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1313 Explosives and detonators outside of magazines....

2014-07-01

402

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Damaged or deteriorated explosives and detonators. 75.1328 Section...STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1328 Damaged or deteriorated explosives and detonators. (a) Damaged...

2013-07-01

403

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Explosives and detonators outside of magazines. 75...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1313 Explosives and detonators outside of magazines....

2011-07-01

404

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Damaged or deteriorated explosives and detonators. 75.1328 Section...STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1328 Damaged or deteriorated explosives and detonators. (a) Damaged...

2014-07-01

405

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Explosives and detonators in underground magazines...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1312 Explosives and detonators in underground...

2011-07-01

406

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Damaged or deteriorated explosives and detonators. 75.1328 Section...STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1328 Damaged or deteriorated explosives and detonators. (a) Damaged...

2012-07-01

407

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Explosives and detonators in underground magazines...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1312 Explosives and detonators in underground...

2013-07-01

408

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Explosives and detonators in underground magazines...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1312 Explosives and detonators in underground...

2010-07-01

409

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Explosives and detonators outside of magazines. 75...SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1313 Explosives and detonators outside of magazines....

2010-07-01

410

JAGUAR Procedures for Detonation Behavior of Explosives Containing Boron  

NASA Astrophysics Data System (ADS)

The JAGUAR product library was expanded to include boron and boron containing products. Relationships of the Murnaghan form for molar volumes and derived properties were implemented in JAGUAR. Available Hugoniot and static volumertic data were analyzed to obtain constants of the Murnaghan relationship for solid boron, boron oxide, boron nitride, boron carbide, and boric acid. Experimental melting points were also utilized with optimization procedures to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX - boron mixtures calculated with these relationships using JAGUAR are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that boron mixtures may exhibit eigenvalue detonation behavior, as observed by aluminized combined effects explosives, with higher detonation velocities than would be achieved by a classical Chapman-Jouguet detonation. Analyses of calorimetric measurements for RDX - boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the energy output obtained from the detonation of the formulation.

Stiel, Leonard; Baker, Ernest; Capellos, Christos

2009-06-01

411

Cellular Structure and Oscillating Behavior of PBX Detonations  

NASA Astrophysics Data System (ADS)

Efforts are aimed on bridging experimental and theoretical studies of localizations/instabilities manifested in detonation reaction zone (DRZ) at micro-, meso-, and macro-scale. In molecular level, the theoretical/computational studies of detonation (RDX, HMX) show: reaction localizations onset/growth is caused by kinetic nonequilibrium stimulated by different levels of activation barriers/reaction energies at bonds dissociation processes (C-NH2, C-NO2, C=C). At micro- and meso-scale levels, leading role of kinetic nonequilibrium in reaction localizations onset was established in experiments with single beta-HMX crystals-in-binder subjected to 20 GPa-shock and PBX detonation. Reaction localizations and further ejecta formation were spatially resolved by 96-channel optical analyzer at simultaneous recording reaction light and stress field around crystal. Spatially-resolved measurements reveal fundamental role of shear-strain in triggering initiation chemistry. At macro-scale level, formation of the cell-structures and oscillating detonation regimes revealed in HMX- and RDX-based PBXs at wide variation of grain-sizes, wt. % filler/binder, residual micro-voids and binder nature. Emphasizes placed on effect of DRZ-induced radiation upon oscillating regimes of detonation front motion.

Plaksin, Igor; Mendes, Ricardo

2013-03-01

412

Close-in Blast Waves from Spherical Charges*  

NASA Astrophysics Data System (ADS)

We study the close-in blast waves created by the detonation of spherical high explosives (HE) charges, via numerical simulations with our Arbitrary-Lagrange-Eulerian (ALE3D) code. We used a finely-resolved, fixed Eulerian 2-D mesh (200 ?m per cell) to capture the detonation of the charge, the blast wave propagation in air, and the reflection of the blast wave from an ideal surface. The thermodynamic properties of the detonation products and air were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. The results were analyzed to evaluate the: (i) free air pressure-range curves: ?ps(R), (ii) free air impulse curves, (iii) reflected pressure-range curves, and (iv) reflected impulse-range curves. A variety of explosives were studied. Conclusions are: (i) close-in (R<10;cm/g^1/3), each explosive had its own (unique) blast wave (e.g., ?ps(R,;HE)˜a/R^n, where n is different for each explosive); (ii) these close-in blast waves do not scale with the ``Heat of Detonation'' of the explosive (because close-in, there is not enough time to fully couple the chemical energy to the air via piston work); (iii) instead they are related to the detonation conditions inside the charge. Scaling laws will be proposed for such close-in blast waves. *This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Howard, William; Kuhl, Allen

2011-06-01

413

Explosive plane-wave lens  

DOEpatents

An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive. 3 figs., 3 tabs.

Marsh, S.P.

1987-03-12

414

Explosive plane-wave lens  

DOEpatents

An explosive plane-wave air lens which enables a spherical wave form to be converted to a planar wave without the need to specially machine or shape explosive materials is described. A disc-shaped impactor having a greater thickness at its center than around its periphery is used to convert the spherical wave into a plane wave. When the wave reaches the impactor, the center of the impactor moves first because the spherical wave reaches the center of the impactor first. The wave strikes the impactor later in time as one moves radially along the impactor. Because the impactor is thinner as one moves radially outward, the velocity of the impactor is greater at the periphery than at the center. An acceptor explosive is positioned so that the impactor strikes the acceptor simultaneously. Consequently, a plane detonation wave is propagated through the acceptor explosive. 4 figs.

Marsh, S.P.

1988-03-08

415

Sensitization of Hydrocarbon-Oxygen Mixtures to Detonation via Cool Flame Oxidation  

Microsoft Academic Search

The effect of cool flame partial oxidation on the detonation sensitivity of hydrocarbons was experimentally investigated. Sensitivity to detonation was quantified by measuring the detonation cell-size using the smoked-foil technique. A rich pentane oxygen mixture was preheated in a pebble bed before filling a heated glass detonation tube to sub-atmospheric pressure. Cool flame reaction, monitored by a thin K-type thermocouple,

M P Romano; M I Radulescu; A J Higgins; J H S Lee; W J Pitz; C K Westbrook

2001-01-01

416

Failure and re-initiation detonation phenomena in NM/PMMA-GMB mixtures  

NASA Astrophysics Data System (ADS)

The addition of a small amount (less than 1%) of glass micro balloons (GMB) on NM/PMMA mixture strongly reduces the failure thickness and increases the detonation sensitivity. A corner turning experiments have been used to gain an insight onto the failure and re-initiation phenomena of NM/PMMA-GMB mixtures. The printed erosion figure on a polished copper plate, used as an witness surface, allows to identify the trajectories not only at the cone of shock oblique waves but also in dark zones around the corner, as well as the re-initiation points. The dark zone and the angle of the cone depends on the impedance of confinement. The original set up has been modified from the corner by fixing a thin sheet of kapton barrier (50 micron thickness) at different angles. This barrier allows the almost integral transmission of normal stress and reduces drastically the shear stress level. Consequently it changes the original pattern of shear stress and zones of initiation. Near the corner, in spite of the influence of GMB, the energy release is not high enough to reach a detonation regime.

Gois, J. C.; Campos, J.; Plaksin, I.; Mendes, R.

1997-07-01

417

Optimal Area Profiles for Ideal Single Nozzle Air-Breathing Pulse Detonation Engines  

NASA Technical Reports Server (NTRS)

The effects of cross-sectional area variation on idealized Pulse Detonation Engine performance are examined numerically. A quasi-one-dimensional, reacting, numerical code is used as the kernel of an algorithm that iteratively determines the correct sequencing of inlet air, inlet fuel, detonation initiation, and cycle time to achieve a limit cycle with specified fuel fraction, and volumetric purge fraction. The algorithm is exercised on a tube with a cross sectional area profile containing two degrees of freedom: overall exit-to-inlet area ratio, and the distance along the tube at which continuous transition from inlet to exit area begins. These two parameters are varied over three flight conditions (defined by inlet total temperature, inlet total pressure and ambient static pressure) and the performance is compared to a straight tube. It is shown that compared to straight tubes, increases of 20 to 35 percent in specific impulse and specific thrust are obtained with tubes of relatively modest area change. The iterative algorithm is described, and its limitations are noted and discussed. Optimized results are presented showing performance measurements, wave diagrams, and area profiles. Suggestions for future investigation are also discussed.

Paxson, Daniel E.

2003-01-01

418

Flying-plate detonator using a high-density high explosive  

DOEpatents

A flying-plate detonator containing a high-density high explosive such as benzotrifuroxan (BTF). The detonator involves the electrical explosion of a thin metal foil which punches out a flyer from a layer overlying the foil, and the flyer striking a high-density explosive pellet of BTF, which is more thermally stable than the conventional detonator using pentaerythritol tetranitrate (PETN).

Stroud, John R. (Livermore, CA); Ornellas, Donald L. (Livermore, CA)

1988-01-01

419

Energy Output of Insensitive High Explosives by Measuring the Detonation Products  

Microsoft Academic Search

The detonation products of high explosives are dependent on pressure and also on the confinement under which the detonation reaction proceeds. To determine the detonation products of less sensitive high explosives such as trinitrotoluene\\/nitroguanidine and polymer bonded explosive charges with polybutadiene binder containing cyclotrimethylene trinitramine, together with or without aluminium, experiments have been performed in a stainless steel chamber of

C. Storm; F. Volk; W. Byers Brown; P. Gray

1992-01-01

420

Nonideal detonation and initiation behavior of a composite solid rocket propellant. [HMX/AP/Al  

SciTech Connect

Shock initiation and detonation behavior of an HMX/AP/Al rocket propellant were studied for nonideal character. Low detonation velocities and unusual shock initiation behavior were observed. Failure to propagate steady detonation in cylinders of the propellant was also noted.

Dick, J.J.

1981-01-01

421

Introduction: Perspectives on Detonation-Based Propulsion DOI: 10.2514/1.26953  

E-print Network

Introduction: Perspectives on Detonation-Based Propulsion DOI: 10.2514/1.26953 DETONATION, a shock, mining, and earth moving. However, since the dawn of the era of high-speed propulsion in the 1940s, an uneven, but ever-present effort has been underway to use detonation in practical propulsion devices

422

American Institute of Aeronautics and Astronautics Numerical Simulation of H2/Air Detonation Using Detailed  

E-print Network

such as Pulse Detonation Engine (PDE) and Supersonic Combustion Ram Jet engine (SCRAM Jet) [1, 2]. On the other even for the current study. Recently, detonation has been applied to the next generation engines- 1 - American Institute of Aeronautics and Astronautics Numerical Simulation of H2/Air Detonation

Löhner, Rainald

423

FILLING OF METHANE/AIR MIXTURE IN A TUBE FOR PULSE DETONATION ENGINES SHRAVANI DWARAKAPALLY  

E-print Network

FILLING OF METHANE/AIR MIXTURE IN A TUBE FOR PULSE DETONATION ENGINES By SHRAVANI DWARAKAPALLY/AIR MIXTURE IN A TUBE FOR PULSE DETONATION ENGINES Shravani Dwarakapally, M.S The University of Texas at Arlington, 2011 Supervising Professor: Dr. Frank K. Lu In pulse detonation engines, filling is a time

Texas at Arlington, University of

424

NUMERICAL STUDY OF CHEMICALLY REACTING VISCOUS FLOW RELEVANT TO PULSED DETONATION ENGINES  

E-print Network

NUMERICAL STUDY OF CHEMICALLY REACTING VISCOUS FLOW RELEVANT TO PULSED DETONATION ENGINES TO PULSED DETONATION ENGINES by TAE-HYEONG YI Presented to the Faculty of the Graduate School RELEVANT TO PULSED DETONATION ENGINES Publication No. Tae-Hyeong Yi, Ph.D. The University of Texas

Texas at Arlington, University of

425

Performance Enhancements on a Pulsed Detonation Engine J.M. Meyers*, F.K. Lu  

E-print Network

1 Performance Enhancements on a Pulsed Detonation Engine J.M. Meyers*, F.K. Lu , D.R. Wilson-frequency pulsed detonations2 . An important technical challenge remains the ability to achieve consistent spiral in a pulsed detonation engine. It is expected that the rapid cycle requirements absent in single

Texas at Arlington, University of

426

A Java-Based Direct Monte Carlo Simulation of a Nano-Scale Pulse Detonation Engine  

E-print Network

A Java-Based Direct Monte Carlo Simulation of a Nano- Scale Pulse Detonation Engine Darryl J. Here, the pulse detonation engine is proposed as a means of propulsion for micro-air vehicles and nano attempting to implement the pulse detonation engine at such small length scales is the dominance of the wall

427

Preliminary Design of a Pulsed Detonation Based Combined Cycle Engine Ramakanth Munipalli*  

E-print Network

1 Preliminary Design of a Pulsed Detonation Based Combined Cycle Engine Ramakanth Munipalli, and (4) A pure Pulsed Detonation Rocket (PDR) mode of operation at high altitude. These modes utilize-mode pulsed detonation based propulsion system has two principal features which distinguish it from existing

Texas at Arlington, University of

428

American Institute of Aeronautics and Astronautics A Pulsed Detonation Based Multimode Engine  

E-print Network

1 American Institute of Aeronautics and Astronautics A Pulsed Detonation Based Multimode Engine Tactical Aeronautics Company Fort Worth, TX Abstract A novel multi-mode implementation of pulsed detonation in Fig. [1]): (1) An ejector augmented pulse detonation rocket for take off to moderate supersonic Mach

Texas at Arlington, University of

429

American Institute of Aeronautics and Astronautics Performance Assessment of Ejector Augmented Pulsed Detonation Rockets  

E-print Network

Pulsed Detonation Rockets Ramakanth Munipalli* , Vijaya Shankar HyPerComp, Inc., 31255, Cedar Valley Dr the pulsed detonation engine concept as a viable alternative high performance propulsion system. As in the case of steady ejector based rockets, the pulsed detonation rockets (PDRs) may also be operated

Texas at Arlington, University of

430

CHEETAH: A fast thermochemical code for detonation  

SciTech Connect

For more than 20 years, TIGER has been the benchmark thermochemical code in the energetic materials community. TIGER has been widely used because it gives good detonation parameters in a very short period of time. Despite its success, TIGER is beginning to show its age. The program`s chemical equilibrium solver frequently crashes, especially when dealing with many chemical species. It often fails to find the C-J point. Finally, there are many inconveniences for the user stemming from the programs roots in pre-modern FORTRAN. These inconveniences often lead to mistakes in preparing input files and thus erroneous results. We are producing a modern version of TIGER, which combines the best features of the old program with new capabilities, better computational algorithms, and improved packaging. The new code, which will evolve out of TIGER in the next few years, will be called ``CHEETAH.`` Many of the capabilities that will be put into CHEETAH are inspired by the thermochemical code CHEQ. The new capabilities of CHEETAH are: calculate trace levels of chemical compounds for environmental analysis; kinetics capability: CHEETAH will predict chemical compositions as a function of time given individual chemical reaction rates. Initial application: carbon condensation; CHEETAH will incorporate partial reactions; CHEETAH will be based on computer-optimized JCZ3 and BKW parameters. These parameters will be fit to over 20 years of data collected at LLNL. We will run CHEETAH thousands of times to determine the best possible parameter sets; CHEETAH will fit C-J data to JWL`s,and also predict full-wall and half-wall cylinder velocities.

Fried, L.E.

1993-11-01

431

Detonation Energies of Explosives by Optimized JCZ3 Procedures  

NASA Astrophysics Data System (ADS)

Procedures for the detonation properties of explosives have been extended for the calculation of detonation energies at adiabatic expansion conditions. Advanced variable metric optimization routines developed by ARDEC are utilized to establish chemical reaction equilibrium by the minimization of the Helmholtz free energy of the system. The use of the JCZ3 equation of state with optimized Exp-6 potential parameters leads to lower errors in JWL detonation energies than the TIGER JCZ3 procedure and other methods tested for relative volumes to 7.0. For the principal isentrope with C-J parameters and freeze conditions established at elevated pressures with the JCZ3 equation of state, best results are obtained if an alternate volumetric relationship is utilized at the highest expansions. Efficient subroutines (designated JAGUAR) have been developed which incorporate the ability to automatically generate JWL and JWLB equation of state parameters. abstract.

Stiel, Leonard; Baker, Ernest

1997-07-01

432

Metallized Gelled Propellants Combustion Experiments in a Pulse Detonation Engine  

NASA Technical Reports Server (NTRS)

A series of combustion tests were performed with metallized gelled JP 8/aluminum fuels in a Pulse Detonation Engine (PDE). Nanoparticles of aluminum were used in the 60 to 100 nanometer diameter. Gellants were also of a nanoparticulate type composed of hydrocarbon alkoxide materials. Using simulated air (a nitrogen-oxygen mixture), the ignition potential of metallized gelled fuels with nanoparticle aluminum was investigated. Ignition of the JP 8/aluminum was possible with less than or equal to a 23-wt% oxygen loading in the simulated air. JP 8 fuel alone was unable to ignite with less than 30 percent oxygen loaded simulated air. The tests were single shot tests of the metallized gelled fuel to demonstrate the capability of the fuel to improve fuel detonability. The tests were conducted at ambient temperatures and with maximal detonation pressures of 1340 psia.

Palaszewski, Bryan; Jurns, John; Breisacher, Kevin; Kearns, Kim

2006-01-01

433

Ferrite core coupled slapper detonator apparatus and method  

DOEpatents

Method and apparatus are provided for coupling a temporally short electric power pulse from a thick flat-conductor power cable into a thin flat-conductor slapper detonator circuit. A first planar and generally circular loop is formed from an end portion of the power cable. A second planar and generally circular loop, of similar diameter, is formed from all or part of the slapper detonator circuit. The two loops are placed together, within a ferrite housing that provides a ferrite path that magnetically couples the two loops. Slapper detonator parts may be incorporated within the ferrite housing. The ferrite housing may be made vacuum and water-tight, with the addition of a hermetic ceramic seal, and provided with an enclosure for protecting the power cable and parts related thereto.

Boberg, Ralph E. (Livermore, CA); Lee, Ronald S. (Livermore, CA); Weingart, Richard C. (Livermore, CA)

1989-01-01

434

Ferrite core coupled slapper detonator apparatus and method  

DOEpatents

Method and apparatus are provided for coupling a temporally short electric power pulse from a thick flat-conductor power cable into a thin flat-conductor slapper detonator circuit. A first planar and generally circular loop is formed from an end portion of the power cable. A second planar and generally circular loop, of similar diameter, is formed from all or part of the slapper detonator circuit. The two loops are placed together, within a ferrite housing that provides a ferrite path that magnetically couples the two loops. Slapper detonator parts may be incorporated within the ferrite housing. The ferrite housing may be made vacuum and water-tight, with the addition of a hermetic ceramic seal, and provided with an enclosure for protecting the power cable and parts related thereto. 10 figs.

Boberg, R.E.; Lee, R.S.; Weingart, R.C.

1989-08-01

435

Curved detonation fronts in solid explosives: Collisions and boundary interactions  

SciTech Connect

Detonation Shock Dynamics (DSD) can be used to model the effects that shock curvature, {kappa}, has oil detonation speed, D{sub n}({kappa}). At the edges of the explosive, D{sub n}({kappa}) is supplemented with boundary conditions. By direct numerical simulation (DNS). The authors study how the reaction zone interacts with the edge. DSD theory has been integrated with the level-set method of Osher and Sethian and the Los Alamos DNS code Mesa to create a powerful tool for simulating complex explosive containing systems.

Bdzil, J.B. [Los Alamos National Lab., NM (United States); Aslam, T.D.; Stewart, D.S. [Univ. of Illinois, Urbana, IL (United States). TAM Dept.

1995-09-01

436

The equation of state of predominant detonation products  

NASA Astrophysics Data System (ADS)

The equation of state of detonation products, when incorporated into an experimentally grounded thermochemical reaction algorithm can be used to predict the performance of explosives. Here we report laser based Impulsive Stimulated Light Scattering measurements of the speed of sound from a variety of polar and nonpolar detonation product supercritical fluids and mixtures. The speed of sound data are used to improve the exponential-six potentials employed within the Cheetah thermochemical code. We will discuss the improvements made to Cheetah in terms of predictions vs. measured performance data for common polymer blended explosives. Accurately computing the chemistry that occurs from reacted binder materials is one important step forward in our efforts.

Zaug, Joseph; Crowhurst, Jonathan; Bastea, Sorin; Fried, Laurence

2009-06-01

437

Measurement of effective blast energy for direct initiation of spherical gaseous detonations from high-voltage spark discharge  

NASA Astrophysics Data System (ADS)

In this study, effective energy from spark discharge for direct blast initiation of spherical gaseous detonations is investigated. In the experiment, direct initiation of detonation is achieved via a spark discharge from a high-voltage and low-inductance capacitor bank and the spark energy is estimated from the analysis of the current output. To determine the blast wave energy from the powerful spark, the time-of-arrival of the blast wave in air is measured at different radii using a piezoelectric pressure transducer. Good agreement is found in the scaled blast trajectories, i.e., scaled time c o· t/ R o where c o is the ambient sound speed, as a function of blast radius R s/ R o between the numerical simulation of a spherical blast wave from a point energy source and the experimental results where the explosion length scale R o is computed using the equivalent spark energy from the first 1/4 current discharge cycle. Alternatively, by fitting the experimental trajectories data, the blast energy estimated from the numerical simulation appears also in good agreement with that obtained experimentally using the 1/4 cycle criterion. Using the 1/4 cycle of spark discharge for the effective energy, direct initiation experiments of spherical gaseous detonations are carried out to determine the critical initiation energy in C2H2-2.5O2 mixtures with 70 and 0% argon dilution. The experimental results obtained from the 1/4 cycle of spark discharge agree well with the prediction from two initiation models, namely, the Lee's surface energy model and a simplified work done model. The main source of discrepancy in the comparison can be explained by the uncertainty of cell size measurement which is needed for both the semi-empirical models.

Zhang, B.; Ng, H. D.; Lee, J. H. S.

2012-01-01

438

The Detonation Mechanism of the Pulsationally-Assisted Gravitationally-Confined Detonation Model of Type Ia Supernovae  

E-print Network

We describe the detonation mechanism comprising the "Pulsationally Assisted" Gravitationally Confined Detonation (GCD) model of Type Ia supernovae (SNe Ia). This model is analogous to the previous GCD model reported in Jordan (2008); however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final energy releases and nickel-56 yields conform better to observational values than is the case for the "classical" GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initia...

Jordan, G C; Fisher, R T; Townsley, D M; Meakin, C; Weide, K; Reid, L B; Norris, J; Hudson, R; Lamb, D Q

2012-01-01

439

Non-Ideal Detonation Properties of Ammonium Nitrate and Activated Carbon Mixtures  

NASA Astrophysics Data System (ADS)

To obtain a better understanding of detonation properties of ammonium nitrate (AN) and activated carbon (AC) mixtures, steel tube tests with several diameters were carried out for various compositions of powdered AN and AC mixtures and the influence of the charge diameter on the detonation velocity was investigated. The results showed that the detonation velocity increased with the increase of the charge diameter. The experimentally observed values were far below the theoretically predicted values made by the thermodynamic CHEETAH code and they showed so-called non-ideal detonation. The extrapolated detonation velocity of stoichiometric composition to the infinite diameter showed a good agreement with the theoretical value.

Miyake, Atsumi; Echigoya, Hiroshi; Kobayashi, Hidefumi; Ogawa, Terushige; Katoh, Katsumi; Kubota, Shiro; Wada, Yuji; Ogata, Yuji

440

A numerical study of two- and three-dimensional detonation dynamics of pulse detonation engine by the CE\\/SE method  

Microsoft Academic Search

In this paper, the CE\\/SE method is developed to simulate the two- and three-dimensional flow-field of Pulse Detonation Engine (PDE). The conservation equations with stiff source terms for chemical reaction are solved in two steps. The detailed analysis of computational results of a PDE with a single detonation tube and a PDE with five detonation tubes are given in this

Chunsheng Weng; Jay P. Gore

2005-01-01

441

Front curvature rate stick measurements and detonation shock dynamics calibration for PBX 9502 over a wide temperature range  

SciTech Connect

Detonation velocity and wave shape are measured for PBX 9502 (95 wt.% TATB, 5 wt.% Kel-F 800) rate sticks at the temperatures {minus}55, 25, and 75 C. At each temperature three different diameters were fired: 50 mm, 18 mm, and 8, 10, and 12 mm respectively for the hot, ambient, and cold sticks. The measured wave shapes are fit with an analytic form and the fitting parameters are tabulated along with thermal expansion and diameter effect data. The simplest detonation shock dynamics (DSD) model assumes a unique calibration function relating the local normal wave speed D{sub n} to the local total curvature {kappa}. The data confirm this notion for sufficiently small curvature, but at large curvature the curves for different charge diameters diverge. Global optimization is used to determine a best single D{sub n}-{kappa} function at each initial temperature T{sub 0}. From these curves a D{sub n}({kappa},T{sub 0}) calibration surface is generated that allows computation of problems with temperature gradients.

Hill, L.G.; Bdzil, J.B.; Aslam, T.D.

1998-12-31

442

Effects of electrostatic discharge on the performance of exploding bridgewire detonators  

NASA Astrophysics Data System (ADS)

The performance of exploding bridgewire detonators affected by electrostatic discharge (ESD) were studied by microfocus X-ray industrial computed tomography (?CT), and high voltage stimulus to detonators was provided by an ESD simulator. Two stimulation modes were investigated, and the performance indexes of detonators after ESD were tested. The results show that there was no obvious change in bridge resistance when detonators were simulated by the mode of Pin-Pin, while the primary explosive of detonators was partly damaged by the mode of pin-shell, and the performance indexes of 2 detonators were affected by ESD. The reasons for this phenomenon were analyzed. This work contributes to understanding the performance of exploding bridgewire detonators affected by ESD.

Li, Zhipeng; Liu, Ying; Zhang, Panjun; Lv, Zijian; Tian, Yong

2013-03-01

443

The Initiation and Propagation of Helium Detonations in White Dwarf Envelopes  

E-print Network

Detonations in helium-rich envelopes surrounding white dwarfs have garnered attention as triggers of faint thermonuclear ".Ia" supernovae and double detonation Type Ia supernovae. However, recent studies have found that the minimum size of a hotspot that can lead to a helium detonation is comparable to, or even larger than, the white dwarf's pressure scale height, casting doubt on the successful ignition of helium detonations in these systems. In this paper, we examine the previously neglected effects of C/O pollution and a full nuclear reaction network, and we consider hotspots with spatially constant pressure in addition to constant density hotspots. We find that the inclusion of these effects significantly decreases the minimum hotspot size for helium-rich detonation ignition, making detonations far more plausible during turbulent shell convection or during double white dwarf mergers. The increase in burning rate also decreases the minimum shell mass in which a helium detonation can successfully propagate ...

Shen, Ken J

2014-01-01

444

Formic acid as a detonation product. [CHNO explosives  

SciTech Connect

The TIGER code, with BKWR as the equation of state, predicts values higher than experimental at all densities. Adding formic acid to the library of expected products of detonation used in TIGER calculations lowers the calculated detonation velocities of CHNO explosives at densities near the TMD. With BKWR this results in closer agreement with experimental data in this region for HMX, PETN, and TNT. The calculated velocities of PETN and TNT are still 1 to 2% higher than experimental values. Using the JCZ3 EOS, adjusted to give an experimental value for HMX, the velocities predicted for PETN and TNT are somewhat lower than experimental. Neither EOS has a significant effect at low densities where TIGER calculates velocities too high with or without formic acid. It is also observed that there is a change in slope in the BKWR detonation velocity vs density curve where solid carbon appears in the calculated products. The predicted products of detonation ar significantly different for the two equations of state. At this time formic acid cannot be ruled out as a possible product. We are suggesting that experimental tests be undertaken to resolve the question. 6 refs., 2 figs., 1 tab.

Crawford, P.C.; Lee, E.L.

1986-06-13

445

Detonation and combustion of explosives: A selected bibliography  

SciTech Connect

This bibliography consists of citations pertinent to the subjects of combustion and detonation of energetic materials, especially, but not exclusively, of secondary solid high explosives. These references were selected from abstracting sources, conference proceedings, reviews, and also individual works. The entries are arranged alphabetically by first author and numbered sequentially. A keyword index is appended.

Dobratz, B. [comp.

1998-08-01

446

Existence of Detonations for Large Values of the Rate Parameter  

Microsoft Academic Search

Recent investigations of idealized Navier-Stokes detonation structure have left unresolved the existence and nature of flow solutions in the case of very fast reactions. By formulating the problem explicitly in terms of a specified initial state and a specified hot boundary mass velocity wP (relative to the unreacted explosive), it is shown that suitable ``steady'' flows exist in all cases,

W. W. Wood

1963-01-01

447

The effect of detonation curvature on cylindrical wall motion  

NASA Astrophysics Data System (ADS)

In the large scale analysis of explosive response, discrepancies have been found between the results predicted by a computer model using various sets of equation of state parameters derived from different experiments. In this report, we will present recent progress toward determining possible reasons for the differences. The system that we have modeled is the cylinder test. Numerous researchers have used this test to study the work potential of detonating explosives for the transverse expansion of metals. One of the original purposes for the development of the test was for the determination of equations of state for detonation products of explosives. The method that is used to determine the parameters for these empirical equations of state, is to iteratively simulate the detonating explosive expansion using a two dimensional hydrodynamic code, adjust the parameters, and repeat until a 'best fit' to the experimental results is obtained. We will, in this present report, explore a small part of this problem. We will concentrate on the effect of the material that is used in the all of the cylinder, the effect of detonation front curvature, and how the curvature might influence the cylindrical wall expansion.

Aldis, D. F.; Quirk, W.; Breithaupt, R. D.

1991-06-01

448

The effect of detonation curvature on cylindrical wall motion  

SciTech Connect

In the large scale analysis of explosive response, discrepancies have been found between the results predicted by a computer models using various sets of equation of state parameters derived from different experiments. In this report, we will present recent progress toward determining possible reasons for the differences. The system that we have modeled in this study is the cylinder test. Numerous researchers have used this test to study the work potential of detonating explosives for the transverse expansion of metals. One of the original purposes for the development of the test was for the determination of equations of state for detonation products of explosives. The method that is used to determine the parameters for these empirical equations of state, is to iteratively simulate the detonating explosive expansion using a two dimensional hydrodynamic code, adjust the parameters, and repeat until a best fit'' to the experimental results is obtained. We will, in this present report, explore a small part of this problem. We will concentrate on the effect of the material that is used in the all of the cylinder, the effect of detonation front curvature, and how the curvature might influence the cylindrical wall expansion. 8 refs., 6 figs.

Aldis, D.F.; Quirk, W.; Breithaupt, R.D.

1991-06-04

449

Transplutonium elements processed from rock debris of underground detonations  

NASA Technical Reports Server (NTRS)

Six-step chemical processing method extracts minute quantities of transplutonium elements found in rock debris following a nuclear detonation. The process consists of dissolution of rock, feed preparation, liquid-liquid extraction, final purification of transplutonium elements and plutonium, and separation of the transplutonium elements.

Bloomquist, C. A. A.; Harvey, H. W.; Hoh, J. C.; Horwitz, E. P.

1969-01-01

450

6. BUILDING NO. 232, ORDNANCE FACILITY (DETONATOR LOADING), LOOKING SOUTHEAST ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. BUILDING NO. 232, ORDNANCE FACILITY (DETONATOR LOADING), LOOKING SOUTHEAST AT STRUCTURE AND BLAST BARRICADES. BUILDING NO. 232-C VISIBLE BEHIND BARRICADE AT LEFT. - Picatinny Arsenal, 200 Area, Shell Component Loading, State Route 15 near I-80, Dover, Morris County, NJ

451

Detonation equation of state at LLNL, 1995. Revision 3  

SciTech Connect

JWL`s and 1-D Look-up tables are shown to work for ``one-track`` experiments like cylinder shots and the expanding sphere. They fail for ``many-track`` experiments like the compressed sphere. As long as the one-track experiment has dimensions larger than the explosive`s reaction zone and the explosive is near-ideal, a general JWL with R{sub 1} = 4.5 and R{sub 2} = 1.5 can be constructed, with both {omega} and E{sub o} being calculated from thermochemical codes. These general JWL`s allow comparison between various explosives plus recalculation of the JWL for different densities. The Bigplate experiment complements the cylinder test by providing continuous oblique angles of shock incidence from 0{degrees} to 70{degrees}. Explosive reaction zone lengths are determined from metal plate thicknesses, extrapolated run-to-detonation distances, radius size effects and detonation front curvature. Simple theories of the cylinder test, Bigplate, the cylinder size effect and detonation front curvature are given. The detonation front lag at the cylinder edge is shown to be proportional to the half-power of the reaction zone length. By calibrating for wall blow-out, a full set of reaction zone lengths from PETN to ANFO are obtained. The 1800--2100 K freezing effect is shown to be caused by rapid cooling of the product gases. Compiled comparative data for about 80 explosives is listed. Ten Chapters plus an Appendix.

Souers, P.C.; Wu, B.; Haselman, L.C. Jr.

1996-02-01

452

Performance of a Pulse Detonation Engine (PDE) Driven Ejector  

Microsoft Academic Search

An analysis of a pulse detonation engine (PDE) driven ejector was performed. Thrust augmentation and specific impulse gains provided by a constant area cross section ejector were computed. Arrange of partial tube fill fractions and ejector diameters were simulated in this study. Important issues associated with the imposed exit boundary conditions were addressed. A rapid decrease in the PDE -

Ephraim Gutmark; Daniel Allgood; Viswanath Katta

2002-01-01

453

Experiment Research of Autonomous Driving Valve for Pulse Detonation Engine  

Microsoft Academic Search

This research proposed the principle of the autonomous driving valve and manufactured the experimental model. This valve composed of only three parts: a piston, a cylinder, and a spring. It is extremely simple and expected mass flow per unit mass is high. In fact, it is specialized for Pulse Detonation Rocket Engine. We established the mechanical model of the valve

Ken Matsuoka

2008-01-01

454

Study on Inflow-Drive Valves for Pulse Detonation Engines  

Microsoft Academic Search

In the present study, a dynamics model of an inflow-drive valve for pulse detonation engines (PDEs) is proposed, in which system the inflow of the valve periodically drives the valve piston. Since the inflow-drive valve needs no energy source to drive the piston, the mass flow rate divided by the valve mass is relatively large, and the response time for

Hiroyuki Yamaguchi; Ken Matsuoka; Jun Yageta; Jiro Kasahara

2009-01-01

455

Operational Issues Affecting the Practical Implementation of Pulsed Detonation Engines  

Microsoft Academic Search

Pulsed detonation engines are slated to be the engines of the future promising better efficiencies and high Mach number applications. There are presently many centers of experimental PDE studies around the world. Most of the studies involve single shot and very short duration test runs. This paper looks at some of the issues faced by engineers studying PDEs, including issues

Philip K. Panicker; Donald R. Wilson; Frank K. Lu

456

The Fluid Dynamics of a Pulse Detonation Engine-II  

Microsoft Academic Search

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Last year, we showed that the fluid dynamics of an idealized PDE, consisting of a tube closed at one end and open at the other is quite complex and depends strongly on the boundary conditions at the open

K. Kailasanath; Gopal Patnaik; Chiping Li

2001-01-01

457

The Fluid Dynamics of a Pulse Detonation Engine-IV  

Microsoft Academic Search

Pulsed Detonation Engines (PDEs) have received considerable attention recently because they have the potential to make a major impact in aerospace propulsion. Previously, the fluid dynamics of an idealized PDE, consisting of a tube closed at one end and open at the other has been presented. Typically, gaseous fuels are used in both experiments and simulations. However, for most practical

K. Kailasanath; S. Cheatham

2003-01-01

458

An experimental and computational study of pulse detonation engines  

Microsoft Academic Search

Research studies investigating the performance optimization and fundamental physics of pulse detonation engines (PDE) were performed. Experimental and computational methods were developed and used in these studies. Four primary research tasks were established. The first research task was to obtain detailed measurements of a PDE exhaust plume for a variety of operating conditions and engine geometries. Shadowgraph visualizations in conjunction

Daniel C. Allgood

2004-01-01