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1

Experimental studies of laser supported detonation waves  

Microsoft Academic Search

Recent work in ground-to-orbit laser propulsion has focused on detonation wave thrusters driven by pulsed infrared lasers. In this concept, a pulsed laser is used to vaporize a small amount of solid propellant; a second laser pulse then drives a detonation wave through this vapor, substantially raising its temperature. Thermal energy is converted to thrust by the expansion of this

C. J. Rollins; D. I. Rosen; M. Gauthier; C. Goldey

1990-01-01

2

Experimental studies of laser supported detonation waves  

SciTech Connect

Recent work in ground-to-orbit laser propulsion has focused on detonation wave thrusters driven by pulsed infrared lasers. In this concept, a pulsed laser is used to vaporize a small amount of solid propellant; a second laser pulse then drives a detonation wave through this vapor, substantially raising its temperature. Thermal energy is converted to thrust by the expansion of this hot vapor. Several aspects of the physics of these thrusters have recently been explored theoretically and with the aid of numerical models. Many of the theoretical predictions can be tested in the laboratory. We report here some results from on-going experiments probing the physics of detonation wave thrusters. Included are spatially and temporally resolved measurements of radiance and opacity of absorption waves. We also present data on target mass loss and momentum transfer, and discuss the importance of the measured quantities in the design of a useful thruster.

Rollins, C.J.; Rosen, D.I.; Gauthier, M.; Goldey, C. (Physical Sciences, Inc., P.O. Box 3100, Andover, Massachusetts 01810 (United States))

1990-07-30

3

Experimental studies of laser supported detonation waves  

NASA Astrophysics Data System (ADS)

Recent work in ground-to-orbit laser propulsion has focused on detonation wave thrusters driven by pulsed infrared lasers. In this concept, a pulsed laser is used to vaporize a small amount of solid propellant; a second laser pulse then drives a detonation wave through this vapor, substantially raising its temperature. Thermal energy is converted to thrust by the expansion of this hot vapor. Several aspects of the physics of these thrusters have recently been explored theoretically and with the aid of numerical models. Many of the theoretical predictions can be tested in the laboratory. We report here some results from on-going experiments probing the physics of detonation wave thrusters. Included are spatially and temporally resolved measurements of radiance and opacity of absorption waves. We also present data on target mass loss and momentum transfer, and discuss the importance of the measured quantities in the design of a useful thruster.

Rollins, C. J.; Rosen, D. I.; Gauthier, M.; Goldey, C.

1990-07-01

4

Experimental studies of laser supported detonation waves  

NASA Astrophysics Data System (ADS)

Recent work in ground-to-orbit laser propulsion has focused on detonation wave thrusters driven by pulsed infrared lasers. In this concept, a pulsed laser is used to vaporize a small amount of solid propellant; a second laser pulse then drives a detonation wave through this vapor, substantially raising its temperature. Thermal energy is converted to thrust by the expansion of this hot vapor. Several aspects of the physics of these thrusters have recently been explored theoretically and with the aid of numerical models. Many of the theoretical predictions can be tested in the laboratory. Results from on-going experiments probing the physics of detonation wave thrusters are reported. Included are spatially and temporally resolved measurements of radiance and opacity of absorption waves. Data on target mass loss and momentum transfer are reported and the importance of the measured quantities in the design of a useful thruster is discussed.

Rollins, C. J.; Rosen, D. I.; Gauthier, M.; Goldey, C.

5

Energy Absorption Structure of Laser Supported Detonation Wave  

Microsoft Academic Search

In Repetitive Pulsed (RP) laser propulsion, when the high energy laser beam is focused in the thruster, Laser Supported Detonation (LSD) wave is generated. This LSD wave converts the laser energy to the enthalpy of the blast wave, which will then apply impulse to the wall of the thruster. Therefore, the energy absorption structure and sustaining condition of LSD wave

Bin Wang; Toshikazu Yamaguchi; Keigo Hatai; Kimiya Komurasaki; Yoshihiro Arakawa

2010-01-01

6

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

7

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

8

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

9

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

10

Analysis of Laser-Supported Detonation Waves and Laser Beam Propagation in Two Dimensions.  

National Technical Information Service (NTIS)

It is shown that the Flux-Corrected Transport (FCT) algorithm correctly computes the propagation velocity and Chapman-Jouguet pressure for a laser-supported detonation (LSD) wave, even for zone size large compared to the radiation absorption length. A two...

J. R. Triplett M. H. Rice

1978-01-01

11

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

NASA Astrophysics Data System (ADS)

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

2006-05-01

12

Fundamental Properties of Non-equilibrium Laser-Supported Detonation Wave  

NASA Astrophysics Data System (ADS)

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

2004-03-01

13

Laser-Supported Detonation Concept as a Space Thruster  

Microsoft Academic Search

Similar to the concept of pulse detonation engine (PDE), a detonation generated in the ``combustion chamber'' due to incoming laser absorption can produce the thrust basically much higher than the one that a laser-supported deflagration wave can provide. Such a laser-supported detonation wave concept has been theoretically studied by the first author for about 20 years in view of its

Toshi Fujiwara; Takeshi Miyasaka

2004-01-01

14

Laser supported detonation wave source of atomic oxygen for aerospace material testing  

NASA Astrophysics Data System (ADS)

A pulsed high flux source of nearly monoenergetic atomic oxygen has been developed at Physical Sciences Inc. (PSI) to perform accelerated erosion testing of spacecraft materials in a simulated low earth orbit (LEO) environment. Molecular oxygen is introduced into an evacuated conical expansion nozzle at several atmospheres pressure through a pulsed molecular beam valve. A laser induced breakdown is generated in the nozzle throat by a pulsed CO2 TEA laser focused to intensities >~109 W/cm2. The resulting plasma is heated in excess of 20,000 K by the ensuing laser supported detonation wave, and then rapidly expands and cools. The nozzle geometry confines the expansion to promote rapid electron-ion recombination into atomic oxygen. The source generates an atomic oxygen beam with fluxes >~1018 atoms per pulse at 8+/-1.6 km/s with an ion content below 1% for LEO testing. For other applications the beam velocity can be varied over a range from 5 to 13 km/s by changing the discharge conditions. Materials testing has obtained the same surface oxygen enrichment in polyethylene samples as observed on the STS-8 mission, and scanning electron micrographs of the irradiated polymer surfaces reveal an erosion morphology similar to that obtained on low earth orbit.

Krech, Robert H.; Caledonia, George E.

1990-07-01

15

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

16

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

NASA Astrophysics Data System (ADS)

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 CO2 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

2008-04-01

17

Laser-Supported Detonation Concept as a Space Thruster  

NASA Astrophysics Data System (ADS)

Similar to the concept of pulse detonation engine (PDE), a detonation generated in the ``combustion chamber'' due to incoming laser absorption can produce the thrust basically much higher than the one that a laser-supported deflagration wave can provide. Such a laser-supported detonation wave concept has been theoretically studied by the first author for about 20 years in view of its application to space propulsion. The entire work is reviewed in the present paper. The initial condition for laser absorption can be provided by increasing the electron density using electric discharge. Thereafter, once a standing/running detonation wave is formed, the laser absorption can continuously be performed by the classical absorption mechanism called Inverse Bremsstrahlung behind a strong shock wave.

Fujiwara, Toshi; Miyasaka, Takeshi

2004-03-01

18

Laser-Supported Detonation Concept as a Space Thruster  

SciTech Connect

Similar to the concept of pulse detonation engine (PDE), a detonation generated in the 'combustion chamber' due to incoming laser absorption can produce the thrust basically much higher than the one that a laser-supported deflagration wave can provide. Such a laser-supported detonation wave concept has been theoretically studied by the first author for about 20 years in view of its application to space propulsion. The entire work is reviewed in the present paper. The initial condition for laser absorption can be provided by increasing the electron density using electric discharge. Thereafter, once a standing/running detonation wave is formed, the laser absorption can continuously be performed by the classical absorption mechanism called Inverse Bremsstrahlung behind a strong shock wave.

Fujiwara, Toshi [ATES Corporation, Tanaka-cho 1-118-3, Toyota 471-0845 (Japan); Miyasaka, Takeshi [Department of Aerospace Engineering, Nagoya University, Nagoya 464-8603 (Japan)

2004-03-30

19

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

20

Thermonuclear Detonation Wave Structure.  

National Technical Information Service (NTIS)

The structure of a very strong detonation wave (a shock wave followed by a thermonuclear reaction zone) propagating through a deuterium-tritium gas mixture is studied. The shock is sufficiently strong so that it heats the gas to a temperature at which the...

A. L. Fuller R. A. Gross

1968-01-01

21

Thermonuclear Detonation Wave Structure  

Microsoft Academic Search

The structure of a very strong detonation wave (a shock wave followed by a thermonuclear reaction zone) propagating through a deuterium-tritium gas mixture is studied. The shock is sufficiently strong so that it heats the gas to a temperature at which thermonuclear reaction probabilities are large. The characteristic times for collisions and reactions are examined to determine when the von

Ann L. Fuller; Robert A. Gross

1968-01-01

22

Understanding curved detonation waves  

SciTech Connect

The reaction zone of a detonation wave is very small compared to the dynamic length scale for a typical application. Consequently, it is impractical for numerical calculations to fully resolve the reaction zone. A non-zero reaction zone width is critical to describe curved detonation waves because it affects the wave speed. The curvature effect is the result of an the interaction between the rate of energy release and geometric source terms within the reaction zone. When the reaction zone width is determined by the computational cell size rather than the physical scale, the numerics introduces an artificial curvature effect which frequently dominates the physical effect and leads to mesh dependence of simulations. Modified Hugoniot jump conditions are derived which characterize the curvature effect. They express the conservation laws and are not sensitive to the detailed reaction dynamics but instead depend only on the reaction zone width, and averages of pressure and of mass, momentum and energy densities.

Bukiet, B.G. (New Jersey Inst. of Tech., Newark, NJ (United States)); Lackner, K.S.; Menikoff, R. (Los Alamos National Lab., NM (United States))

1993-01-01

23

Understanding curved detonation waves  

SciTech Connect

The reaction zone of a detonation wave is very small compared to the dynamic length scale for a typical application. Consequently, it is impractical for numerical calculations to fully resolve the reaction zone. A non-zero reaction zone width is critical to describe curved detonation waves because it affects the wave speed. The curvature effect is the result of an the interaction between the rate of energy release and geometric source terms within the reaction zone. When the reaction zone width is determined by the computational cell size rather than the physical scale, the numerics introduces an artificial curvature effect which frequently dominates the physical effect and leads to mesh dependence of simulations. Modified Hugoniot jump conditions are derived which characterize the curvature effect. They express the conservation laws and are not sensitive to the detailed reaction dynamics but instead depend only on the reaction zone width, and averages of pressure and of mass, momentum and energy densities.

Bukiet, B.G. [New Jersey Inst. of Tech., Newark, NJ (United States); Lackner, K.S.; Menikoff, R. [Los Alamos National Lab., NM (United States)

1993-06-01

24

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

25

Detonation waves in relativistic hydrodynamics  

SciTech Connect

This paper is concerned with an algebraic study of the equations of detonation waves in relativistic hydrodynamics taking into account the pressure and the energy of thermal radiation. A new approach to shock and detonation wavefronts is outlined. The fluid under consideration is assumed to be perfect (nonviscous and nonconducting) and to obey the following equation of state: {ital p}=({gamma}{minus}1){rho} where {ital p}, {rho}, and {gamma} are the pressure, the total energy density, and the adiabatic index, respectively. The solutions of the equations of detonation waves are reduced to the problem of finding physically acceptable roots of a quadratic polynomial {Pi}({ital X}) where {ital X} is the ratio {tau}/{tau}{sub 0} of dynamical volumes behind and ahead of the detonation wave. The existence and the locations of zeros of this polynomial allow it to be shown that if the equation of state of the burnt fluid is known then the variables characterizing the unburnt fluid obey well-defined physical relations.

Cissoko, M. (Universite Pierre et Marie Curie, Paris VI, Laboratoire de Gravitation et de Cosmologie Relativistes, Institut Henri Poincare, 11 Rue Pierre et Marie Curie, 7500 Paris (France))

1992-02-15

26

The structure of detonation waves in supernovae  

Microsoft Academic Search

The theory of gaseous detonation is applied to thermonuclear detonation waves in supernovae. First, the two-temperature structure of strong shock waves in a dense degenerate plasma is considered. The ion-electron energy transfer rate is calculated for a plasma with arbitrary degeneracy of electrons. It is shown that the non-equilibrium heating of ions is unimportant for detonation. The steady planar one-dimensional

A. M. Khokhlov

1989-01-01

27

Detonation-wave interactions. [PBX-9404  

SciTech Connect

The interaction of laterally colliding, diverging, cylindrical detonation waves in PBX-9404 has been studied using the radiographic machine PHERMEX and the two-dimensional, reactive Lagrangian hydrodynamic code 2DL. The experimentally observed flow could be numerically reproduced using the Forest Fire heterogeneous shock initiation burn model which permits realistic numerical simulation of the burning region of regular and diverging detonation waves, and the interacting detonation waves undergoing regular and Mach reflection. The interaction of two, three, and five colliding, diverging spherical detonation waves in PBX-9404 has been numerically modeled using the three-dimensional, reactive Eulerian hydrodynamic code 3DE. The size and magnitude of the high pressure double, triple, quadruple, and quintuple interactions depends significantly upon the number and relative locations of initiators. The initiation of propagating detonation in the insensitive explosive PBX-9502 by triple shock-wave interaction resulting from three initiators has been studied using the 3DE code with Forest Fire kinetics.

Mader, C.L.

1981-01-01

28

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

29

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

30

Detonation wave initiation of ram accelerator propellants  

Microsoft Academic Search

.   The current ram accelerator operations have shown that data on the ability of the propellants to detonate are required. Previous\\u000a studies examined the efficacy of initiation techniques based on piston impact. The purpose of the present work is to analyze\\u000a the effects of detonation wave transmission from a detonating mixture into a low sensitivity mixture. One-dimensional modeling\\u000a based on

P. Bauer; C. Knowlen

2001-01-01

31

Detonation wave initiation of ram accelerator propellants  

NASA Astrophysics Data System (ADS)

The current ram accelerator operations have shown that data on the ability of the propellants to detonate are required. Previous studies examined the efficacy of initiation techniques based on piston impact. The purpose of the present work is to analyze the effects of detonation wave transmission from a detonating mixture into a low sensitivity mixture. One-dimensional modeling based on the analysis of pressure vs particle velocity for the mixtures is used to interpret experimental data. Furthermore, calculations based on chemical kinetics (CHEMKIN code) are provided. Experimental data together with the modeling of the detonation transmission provide some new insight into the limiting conditions necessary to establish a Chapman-Jouguet (CJ) wave in a detonable mixture.

Bauer, P.; Knowlen, C.

32

Propagation Regimes of Self-Supported Light-Detonation Waves  

Microsoft Academic Search

The light-detonation wave structure is investigated. It is shown that self-supported laser radiation absorption waves can\\u000a propagate in the Jouguet detonation or undercompressed detonation regimes. The conditions of realization of these regimes\\u000a are found numerically. It is shown that the undercompressed detonation regime is realized if the radiation flux is sufficiently\\u000a powerful. In the case of a light-detonation wave this

A. G. Kulikovskii; N. T. Pashchenko

2005-01-01

33

Propagation characteristics of shock waves driven by gaseous detonation waves  

Microsoft Academic Search

We experimentally investigated propagation characteristics of the shock wave driven by a gaseous detonation wave emerging\\u000a from the open end of a cylindrical detonation tube. In the present study, we visualized the shock wave and exhaust flowfields\\u000a using a shadowgraph optical system and we obtained peak overpressure in the tube axial direction and the continuous shape\\u000a transformation of shock waves

S. Kato; S. Hashimoto; A. Uemichi; J. Kasahara; A. Matsuo

2010-01-01

34

Demonstration of Oblique Detonation Wave for Hypersonic Propulsion.  

National Technical Information Service (NTIS)

The Oblique Detonation Wave Engine (ODWE) offers a number of advantages over the Supersonic Combustor Ramjet (SCRAMJET) for hypersonic aeropropulsion. The objective of this program is to obtain data on the stability of the Oblique Detonation Wave (ODW) an...

T. Nakamura M. J. Schuh D. S. Randall T. J. Dahm D. T. Pratt

1989-01-01

35

Reinitiation process of detonation wave behind a slit-plate  

NASA Astrophysics Data System (ADS)

The propagation phenomenon of a detonation wave is particularly interesting, because the detonation wave is composed of a 3D shock wave system accompanied by a reaction front. Thus, the passage of a detonation wave draws cellular patterns on a soot-covered plate. The pressure and temperature behind the detonation wave are extremely high and may cause serious damages around the wave. Therefore, it is of great significance from a safety-engineering point of view to decay the detonation wave with a short distance from the origin. In the present study, experiments using high-speed schlieren photography are conducted in order to investigate the behaviors of the detonation wave diffracting from two slits. The detonation wave produced in a stoichiometric mixture of hydrogen and oxygen is propagated through the slits, and the behaviors behind the slit-plate are investigated experimentally. When a detonation wave diffracts from the slits, a shock wave is decoupled with a reaction front. Since the two shock waves propagate from the slits interact with each other at the center behind the plate, the detonation wave is reinitiated by generating a hot-spot sufficient to cause local explosions. Furthermore, it is clarified that the shock wave reflected from a tube-wall is also capable of reinitiating the detonation wave. The reinitiation distance of the detonation wave from the slit-plate is correlated using a number of cells emerged from each slit.

Obara, T.; Sentanuhady, J.; Tsukada, Y.; Ohyagi, S.

2008-07-01

36

On the Existence of Pathological Detonation Waves  

Microsoft Academic Search

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

Craig M. Tarver

2004-01-01

37

The flow field in a rotating detonation-wave engine  

NASA Astrophysics Data System (ADS)

Rotating detonation-wave engines (RDE) are a form of continuous detonation-wave engine. They potentially provide further gains than an intermittent or pulsed detonation--wave engine (PDE). However, significantly less work has been on this concept when compared to the PDE. In this talk, we present the detailed flow field in an idealized RDE, primarily consisting of two concentric cylinders. A premixed detonable mixture is injected into the annulus between the two concentric cylinders. Once a detonation is initiated, it keeps travelling around in the annulus as long as there is fresh detonable mixture ahead of it. Hence, the injection process is critically important to the stability and performance of the RDE. Furthermore, we show that the flow field is quite complex consisting of multiple shock waves and the outflow is primarily axial, although the detonation-wave is travelling around circumferentially.

Kailasanath, Kazhikathra; Schwer, Douglas

2011-11-01

38

Laser-supported ionization wave in under-dense gases and foams  

SciTech Connect

Propagation of laser-supported ionization wave in homogeneous and porous materials with a mean density less than the critical plasma density is studied theoretically in the one-dimensional geometry. It is shown that the velocity of the ionization wave in a foam is significantly decreased in comparison with the similar wave in a homogeneous fully ionized plasma of the same density. That difference is attributed to the ionization and hydro-homogenization processes forming an under-critical density environment in the front of ionization wave. The rate of energy transfer from laser to plasma is found to be in a good agreement with available experimental data.

Gus'kov, S. Yu. [P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Limpouch, J. [FNSPE, Czech Technical University in Prague, 115 19 Prague 1 (Czech Republic); Nicolaie, Ph.; Tikhonchuk, V. T. [Centre Lasers Intenses et Applications, Universite Bordeaux - CNRS - CEA, Talence 33405 (France)

2011-10-15

39

On the Existence of Pathological Detonation Waves  

Microsoft Academic Search

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

Tarver

2003-01-01

40

Reviews of Topical Problems: Detonation Waves in Gases  

Microsoft Academic Search

1. Introduction 523 2. Structure of detonation wave 524 2.1. Stationary zone of chemical reaction 524 2.2. Rarefaction wave 525 2.3. The Chapman-Jouguet condition 526 2.4. Diverging and converging detonation waves 526 3. Experimental methods for the study of the state of the gas behind the detonation front 527 3.1. Measurement of pressure (pulsed piezoelectric transducers) 527 3.2. Measurement of

R. I. Soloukhin

1964-01-01

41

The quasi-steady regime in critically initiated detonation waves  

Microsoft Academic Search

Experimental work is described on the initiation of spherical detonation waves, in oxyacetylene with various diluents, using an exploding wire and a lead azide pellet as sources. The transition of the spherical blast wave to a detonation, when the source energy is either above or at the critical value, is studied by three methods. Changes in wave structure are inferred

D. H. Edwards; G. Hooper; J. M. Morgan; G. O. Thomas

1978-01-01

42

Detonation Wave Structure of Gases at Elevated Initial Pressures  

Microsoft Academic Search

The characteristic “structure” of gaseous detonation waves, defined here as the spatial variation of the pressure, temperature, density, species concentrations, and velocity within the detonation wave is examined theoretically at elevated initial pressures. The approach taken in this work is to extend the Zel'dovich-von Neumann-Doering (ZND) theory of gas-phase detonation to use real-gas equations of state, Chemkin Real Gas, a

R. G. SCHMITT; P. B. BUTLER

1995-01-01

43

Multidimensional detonation propagation modeled via nonlinear shock wave superposition  

NASA Astrophysics Data System (ADS)

Detonation waves in gases are inherently multidimensional due to their cellular structure, and detonations in liquids and heterogeneous solids are often associated with instabilities and stochastic, localized reaction centers (i.e., hot spots). To explore the statistical nature of detonation dynamics in such systems, a simple model that idealizes detonation propagation as an ensemble of interacting blast waves originating from spatially random point sources has been proposed. Prior results using this model exhibited features that have been observed in real detonating systems, such as anomalous scaling between axisymmetric and two-dimensional geometries. However, those efforts used simple linear superposition of the blast waves. The present work uses a model of blast wave superposition developed for multiple-source explosions (the LAMB approximation) that incorporates the nonlinear interaction of shock waves analytically, permitting the effect of a more physical model of blast wave interaction to be explored. The results are suggestive of a universal behavior in systems of spatially randomized energy sources.

Higgins, Andrew; Mehrjoo, Navid

2010-11-01

44

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

45

Propagation characteristics of shock waves driven by gaseous detonation waves  

NASA Astrophysics Data System (ADS)

We experimentally investigated propagation characteristics of the shock wave driven by a gaseous detonation wave emerging from the open end of a cylindrical detonation tube. In the present study, we visualized the shock wave and exhaust flowfields using a shadowgraph optical system and we obtained peak overpressure in the tube axial direction and the continuous shape transformation of shock waves around the tube open end. We also obtained overpressure histories of the shock wave using piezo-pressure transducers within 201 m from the open end of the tube. We normalized and classified these results by four regions using non-dimensional pressure and distance which are independent of variety of mixture and tube diameter. In the vicinity of the open end of the tube, the shock wave is nearly planar and does not significantly attenuate, and the peak overpressure maintains approximately C-J pressure. Subsequently, the shock wave attenuates rapidly, transforming from quasi-spherical to spherical. Farther from the tube open end, the shock wave propagates with approximately sound characteristic so that the peak overpressure decreases proportional to 1/ r. Eventually, the shock wave begins to attenuate more rapidly than ideal sound attenuation, which may be due to the viscous effect.

Kato, S.; Hashimoto, S.; Uemichi, A.; Kasahara, J.; Matsuo, A.

2010-12-01

46

DDT and detonation waves in dust-air mixtures  

NASA Astrophysics Data System (ADS)

This paper summarizes the studies of DDT and stable detonation waves in dust-air mixtures at the Stosswellenlabor of RWTH Aachen. The DDT process and propagation mechanism for stable heterogeneous dust detonations in air are essentially the same as in the oxygen environment studied previously. The dust DDT process in tubes is composed of a reaction compression stage followed by a reaction shock stage as the pre-detonation process. The transverse waves that couple the shock wave and the chemical energy release are responsible for the propagation of a stable dust-air detonation. However, the transverse wave spacing of dust-air mixtures is much larger. Therefore, DDT and propagation of a stable detonation in most industrial and agricultural, combustible dust-air mixtures require a tube that has a large diameter between 0.1 m and 1 m and a sufficient length-diameter ratio beyond 100, when an appropriately strong initiation energy is used. Two dust detonation tubes, 0.14 m and 0.3 m in diameter, were used for observation of the above-mentioned results in cornstarch, anthraquinone and aluminum dust suspended in air. Smoked-foil technique was also used to measure the cellular structure of dust detonations in the 0.3 m detonation tube.

Zhang, F.; Grönig, H.; van de Ven, A.

47

Adaptive high-resolution simulation of realistic gaseous detonation waves  

SciTech Connect

The numerical approximation of detonation waves in gaseous combustible mixtures is extremely demanding since a wide range of scales needs to be resolved. A dynamically adaptive high-resolution finite volume method is described that has enabled accurately resolved computational investigations of the transient behavior of regularly oscillating detonations in low-pressure hydrogen-oxygen mixtures in realistic two-dimensional geometry.

Deiterding, Ralf [ORNL

2007-01-01

48

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

Microsoft Academic Search

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.

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

2005-01-01

49

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

50

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

51

Reactive Flow Modeling of the Interaction of TATB Detonation Waves with Inert Materials  

Microsoft Academic Search

The Ignition & Growth model for the shock initiation and detonation of solid explosives is applied to calculating the main features of detonation waves in the triaminotrinitrobenzene (TATB) based high explosives LX-17, PBX 9502 and EDC-35. Under detonation conditions, TATB based explosives exhibit reaction zone lengths of 2 to 3 mm depending on the interactions between the detonation wave and

Craig M. Tarver; Estella M. McGuire

2002-01-01

52

Numerical Simulation of Pulse Detonation Wave Engine Phenomena  

NASA Astrophysics Data System (ADS)

This computational study examines transient, reactive compressible flow phenomena associated with the pulse detonation wave engine or PDE. The PDE is an intermittent combustion engine that relies on unsteady (pulsating) detonation wave propagation for combustion and compression elements of the propulsive cycle. The present computations focus on one- and two-dimensional simulations of the generic PDE configuration in which propagating detonation waves are generated periodically within an engine tube, with associated reflected expansion and compression waves which act in periodic fashion to produce high forward thrust. Systematic examination of the effects of reaction zone and computational domain resolution, the combustion reaction mechanism, combustion tube and nozzle length and geometry, and the cycle initiation mechanism is performed.

He, Xing; Karagozian, Ann R.

2001-11-01

53

Two-dimensional detonation waves in Type IA supernovae  

NASA Astrophysics Data System (ADS)

The propagation of two-dimensional nuclear detonation waves in Type Ia supernovae is calculated from Huygens' principle and the resulting flow is then computed with a hydrodynamic code. This has the advantage that one can study asymmetric explosions using wave speeds determined from one-dimensional calculations which include very detailed nuclear chemistry. The method is applied to two cases, the one-dimensional versions of which have previously been considered by Nomoto. We find that the detonation wave forms a pair of cusps which are likely to have a significant effect on both the abundances and the final asymmetry of the expansion.

Wiggins, D. J. R.; Falle, S. A. E. G.

1997-05-01

54

Direct Initiation of Detonation by Non-Ideal Blast Waves.  

National Technical Information Service (NTIS)

This study is a theoretical investigation of the initiation of detonation by nonideal blast waves. The study used the output of the CLOUD program as the source of flow data for blast waves generated by bursting spheres. Each cell that surrounds the bursti...

R. J. Cesarone

1977-01-01

55

Direct initiation of detonation by non-ideal blast waves  

Microsoft Academic Search

This study is a theoretical investigation of the initiation of detonation by nonideal blast waves. The study used the output of the CLOUD program as the source of flow data for blast waves generated by bursting spheres. Each cell that surrounds the bursting sphere is assumed to be reactive with an Arrhenius type kinetic rate law over a temperature range

R. J. Cesarone

1977-01-01

56

Laser-initiated conical detonation wave for supersonic combustion. II  

NASA Astrophysics Data System (ADS)

Further theoretical studies are undertaken of the feasibility of an air-breathing supersonic combustor based on a stabilized, conically configured (oblique) detonation wave. The conical wave is the resultant of the interaction of a train of spherical detonation waves, each directly initiated by a very rapidly repeated pulsed laser, which is tightly focused on a fixed site in a steady uniform supersonic stream of combustible gaseous mixture. Here, the length of an axisymmetric (nearly conical) nozzle required to exhaust the reacted mixture at ambient-atmosphere pressure is estimated by a steady isentropic ideal-gas flow calculation. Then the thrust-to-drag ratio achievable with such a combustor for upper-atmospheric flight is roughly characterized. Finally, proof-of-principle laboratory experiments needed to establish the capacity of existing laser sources to achieve the direct initiation of detonation in hydrogen/air mixtures under conditions of practical interest are outlined.

Fendell, F.; Mitchell, J.; McGregor, R.; Magiawala, K.; Sheffield, M.

1992-01-01

57

Weakly nonlinear dynamics of near-CJ detonation waves  

SciTech Connect

The renewed interest in safety issues for large scale industrial devices and in high speed combustion has driven recent intense efforts to gain a deeper theoretical understanding of detonation wave dynamics. Linear stability analyses, weakly nonlinear bifurcation calculations as well as full scale multi-dimensional direct numerical simulations have been pursued for a standard model problem based on the reactive Euler equations for an ideal gas with constant specific heat capacities and simplified chemical reaction models. Most of these studies are concerned with overdriven detonations. This is true despite the fact that the majority of all detonations observed in nature are running at speeds close to the Chapman-Jouguet (CJ) limit value. By focusing on overdriven waves one removes an array of difficulties from the analysis that is associated with the sonic flow conditions in the wake of a CJ-detonation. In particular, the proper formulation of downstream boundary conditions in the CJ-case is a yet unsolved analytical problem. A proper treatment of perturbations in the back of a Chapman-Jouguet detonation has to account for two distinct weakly nonlinear effects in the forward acoustic wave component. The first is a nonlinear interactionof highly temperature sensitive chemistry with the forward acoustic wave component in a transonic boundary layer near the end of the reaction zone. The second is a cumulative three-wave-resonance in the sense of Majda et al. which is active in the near-sonic burnt gas flow and which is essentially independent of the details of the chemical model. In this work, we consider detonations in mixtures with moderate state sensitivity of the chemical reactions. Then, the acoustic perturbations do not influence the chemistry at the order considered and we may concentrate on the second effect; the three-wave resonance.

Bdzil, J.B. (Los Alamos National Lab., NM (United States)); Klein, R. (Technische Hochschule Aachen (Germany). Inst. fuer Technische Mechanik)

1993-01-01

58

Weakly nonlinear dynamics of near-CJ detonation waves  

SciTech Connect

The renewed interest in safety issues for large scale industrial devices and in high speed combustion has driven recent intense efforts to gain a deeper theoretical understanding of detonation wave dynamics. Linear stability analyses, weakly nonlinear bifurcation calculations as well as full scale multi-dimensional direct numerical simulations have been pursued for a standard model problem based on the reactive Euler equations for an ideal gas with constant specific heat capacities and simplified chemical reaction models. Most of these studies are concerned with overdriven detonations. This is true despite the fact that the majority of all detonations observed in nature are running at speeds close to the Chapman-Jouguet (CJ) limit value. By focusing on overdriven waves one removes an array of difficulties from the analysis that is associated with the sonic flow conditions in the wake of a CJ-detonation. In particular, the proper formulation of downstream boundary conditions in the CJ-case is a yet unsolved analytical problem. A proper treatment of perturbations in the back of a Chapman-Jouguet detonation has to account for two distinct weakly nonlinear effects in the forward acoustic wave component. The first is a nonlinear interactionof highly temperature sensitive chemistry with the forward acoustic wave component in a transonic boundary layer near the end of the reaction zone. The second is a cumulative three-wave-resonance in the sense of Majda et al. which is active in the near-sonic burnt gas flow and which is essentially independent of the details of the chemical model. In this work, we consider detonations in mixtures with moderate state sensitivity of the chemical reactions. Then, the acoustic perturbations do not influence the chemistry at the order considered and we may concentrate on the second effect; the three-wave resonance.

Bdzil, J.B. [Los Alamos National Lab., NM (United States); Klein, R. [Technische Hochschule Aachen (Germany). Inst. fuer Technische Mechanik

1993-02-01

59

Direct Calculation of Wave Implosion for Detonation Initiation in Pulsed Detonation Engines  

Microsoft Academic Search

One- and two-dimensional imploding waves are numerically simulated by using the space- time CESE method. One-dimensional calculations show that a Mach 1.3 converging shock is capable to initiate the detonation in a 2:1:7 H2\\/O2\\/Ar gas mixture, initially at 0.2 standard atmospheric pressure. Results also clearly show a two-shock implosion system, resulting from interactions between the reflected main shock and the

Bao Wang; S.-T. John Yu

60

Laser supported detonation wave source of atomic oxygen for aerospace material testing  

Microsoft Academic Search

A pulsed high flux source of nearly monoenergetic atomic oxygen has been developed at Physical Sciences Inc. (PSI) to perform accelerated erosion testing of spacecraft materials in a simulated low earth orbit (LEO) environment. Molecular oxygen is introduced into an evacuated conical expansion nozzle at several atmospheres pressure through a pulsed molecular beam valve. A laser induced breakdown is generated

Robert H. Krech; George E. Caledonia

1990-01-01

61

Dynamic mode decomposition analysis of detonation waves  

NASA Astrophysics Data System (ADS)

Dynamic mode decomposition is applied to study the self-excited fluctuations supported by transversely unstable detonations. The focus of this study is on the stability of the limit cycle solutions and their response to forcing. Floquet analysis of the unforced conditions reveals that the least stable perturbations are almost subharmonic with ratio between global mode and fundamental frequency ?i/?f = 0.47. This suggests the emergence of period doubling modes as the route to chaos observed in larger systems. The response to forcing is analyzed in terms of the coherency of the four fundamental energy modes: acoustic, entropic, kinetic, and chemical. Results of the modal decomposition suggest that the self-excited oscillations are quite insensitive to vortical forcing, and maintain their coherency up to a forcing turbulent Mach number of 0.3.

Massa, L.; Kumar, R.; Ravindran, P.

2012-06-01

62

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

63

Precursor detonation wave development in ANFO due to aluminum confinement  

Microsoft Academic Search

Detonations in explosive mixtures of ammonium-nitrate-fuel-oil (ANFO) confined by aluminum allow for transport of detonation energy ahead of the detonation front due to the aluminum sound speed exceeding the detonation velocity. The net effect of this energy transport on the detonation is unclear. It could enhance the detonation by precompressing the explosive near the wall. Alternatively, it could decrease the

Scott I Jackson; Charles B Klyanda; Mark Short

2010-01-01

64

Millimeter-wave Driven Shock Wave for a Pulsed Detonation Microwave Rocket  

Microsoft Academic Search

A shock wave driven by millimeter wave ionization can be applied into a pulsed detonation engine as a Microwave Rocket. A high pressure induced inside the thruster generates the thrust, thus the shock wave propagation driven by the plasma is important. In this study, to obtain a different propagating structure, the beam profile was transformed from a Gaussian into a

Toshikazu Yamaguchi; Reiji Komatsu; Masafumi Fukunari; Kimiya Komurasaki; Yasuhisa Oda; Ken Kajiwara; Koji Takahashi; Keishi Sakamoto

2011-01-01

65

Numerical investigation of oblique detonation waves for a shcramjet combustor  

NASA Astrophysics Data System (ADS)

Research in hypersonic airbreathing propulsion strives to provide an efficient, cost-effective alternative to rocket propulsion for space transportation systems. The supersonic combustion ramjet (scramjet) is one of the most common hypersonic airbreathing propulsion concepts, but its massive combustor could have detrimental effects on its efficiency. The shock-induced combustion ramjet (shcramjet) overcomes this drawback by using standing oblique detonation waves (coupled shock-combustion fronts) as a means of nearly instantaneous heat addition. A numerical investigation of standing oblique detonation waves for their use in shcramjet propulsion is the main purpose of this investigation. The laminar, two-dimensional Navier-Stokes equations coupled with non-equilibrium hydrogen/air combustion models based on chemical kinetics are used to represent the physical system. The combustion models are incorporated into an in-house computational fluid dynamics solver based on a shock-capturing scheme by Yee scheme and an approximate factorization algorithm with a dual-time stepping technique to regain time-accuracy. The solver is validated with experimental data found in the literature. A time accurate simulation of the formation of a standing oblique detonation wave (ODW) near the Chapman Jouguet (minimum entropy) condition yields a non-oscillatory, stable structure. The stability of the ODW to inhomogeneities in the oncoming fuel/air mixture is assessed through other time-accurate simulations by artificially introducing small disturbances consisting of pure air just upstream of the ODW structure. The ODW is shown to be resilient to these disturbances: an upstream displacement is observed followed by the return of the ODW to its original position. Steady-state simulations are carried out to determine the effect of laminar boundary layers on ODW structures and properties above and below the Chapman-Jouguet point. A comparison with analogous inviscid simulations shows that the effect is minimal and that the shorter induction distance in laminar flow does not entail a significantly earlier onset of the ODW. A novel shcramjet combustor design that makes use of oblique detonation waves stabilized over wedge-shaped flame-holders and configured such that detonation wave-wall interactions are avoided, is presented and analyzed through steady-state simulations. The design is shown to be a viable one for shcramjet propulsion by means of thrust potential calculations.

Fusina, Giovanni

66

Experimental study on transmission of an overdriven detonation wave from propane/oxygen to propane/air  

SciTech Connect

Two sets of experiments were performed to achieve a strong overdriven state in a weaker mixture by propagating an overdriven detonation wave via a deflagration-to-detonation transition (DDT) process. First, preliminary experiments with a propane/oxygen mixture were used to evaluate the attenuation of the overdriven detonation wave in the DDT process. Next, experiments were performed wherein a propane/oxygen mixture was separated from a propane/air mixture by a thin diaphragm to observe the transmission of an overdriven detonation wave. Based on the characteristic relations, a simple wave intersection model was used to calculate the state of the transmitted detonation wave. The results showed that a rarefaction effect must be included to ensure that there is no overestimate of the post-transmission wave properties when the incident detonation wave is overdriven. The strength of the incident overdriven detonation wave plays an important role in the wave transmission process. The experimental results showed that a transmitted overdriven detonation wave occurs instantaneously with a strong incident overdriven detonation wave. The near-CJ state of the incident wave leads to a transmitted shock wave, and then the transition to the overdriven detonation wave occurs downstream. The attenuation process for the overdriven detonation wave decaying to a near-CJ state occurs in all tests. After the attenuation process, an unstable detonation wave was observed in most tests. This may be attributed to the increase in the cell width in the attenuation process that exceeds the detonability cell width limit. (author)

Li, J.; Lai, W.H. [National Cheng Kung University, Institute of Aeronautics and Astronautics, Tainan (China); Chung, K. [National Cheng Kung University, Aerospace Science and Technology Research Center, Tainan (China); Lu, F.K. [University of Texas at Arlington, Mechanical and Aerospace Engineering Department, Aerodynamics Research Center, TX 76019 (United States)

2008-08-15

67

Measurement of pressure behind a detonation wave front in a heterogeneous gas-film system  

Microsoft Academic Search

Knowledge of the magnitude and profile of the pressure behind a detonation wave front is required for an understanding of the nature of detonation, of the wave structure, and of the processes in the reaction zone. Only a small amount of information has been published [1-3] on pressure measurements in square cross-section pipes during detonation in gas--film systems (gaseous oxidant

A. V. Pinaev

1983-01-01

68

Dynamic numerical simulation of detonation wave of perforating bullet and research of its measuring method  

Microsoft Academic Search

Dynamic numerical simulation of the spreading of detonation wave was made by use of the explicit dynamic finite element analysis program. The results of numerical simulation are in agreement with physical phenomena and laws of spreading of detonation wave. The study indicates that the calculation model and simulation method are reasonable and feasible. The volume of electronic sensor both at

Cao Shan; Zou Kuancheng; Cao Yuxin; Cao Lina; Han Xiuqing

2010-01-01

69

Progress in measuring detonation wave profiles in PBX9501  

SciTech Connect

The authors have measured detonation wave profiles in PBX9501 (95 wt% HMX and 5 wt% binders) using VISAR. Planar detonations were produced by impacting the explosive with projectiles launched in a 72 mm bore gas gun. Particle velocity wave profiles were measured at the explosive/window interface using two VISARs with different fringe constants. Windows with very thin vapor deposited aluminum mirrors were used for all experiments. PMMA windows provided an undermatch, and LiF (Lithium Fluoride) windows provided an overmatch to the explosive, reacted and unreacted. While the present experiments do not have adequate time resolution to adequately resolve the ZND spike condition, they do constrain it to lie between 38.7 and 53.4 Gpa or 2.4 and 3.3 km/s. Accurate knowledge of the CJ state places the reaction zone length at 35 {+-} 12 ns ({approx} 0.3 mm). The present experiments do not show any effect of the window on the reaction zone; both window materials result in the same reaction zone length.

Gustavsen, R.L.; Sheffield, S.A.; Alcon, R.R.

1998-12-31

70

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

71

Hydrodynamic instabilities and transverse waves in propagation mechanism of gaseous detonations  

NASA Astrophysics Data System (ADS)

The present study examines the role of transverse waves and hydrodynamic instabilities mainly, Richtmyer-Meshkov instability (RMI) and Kelvin-Helmholtz instability (KHI) in detonation structure using two-dimensional high-resolution numerical simulations of Euler equations. To compare the numerical results with those of experiments, Navier-Stokes simulations are also performed by utilizing the effect of diffusion in highly irregular detonations. Results for both moderate and low activation energy mixtures reveal that upon collision of two triple points a pair of forward and backward facing jets is formed. As the jets spread, they undergo Richtmyer-Meshkov instability. The drastic growth of the forward jet found to have profound role in re-acceleration of the detonation wave at the end of a detonation cell cycle. For irregular detonations, the transverse waves found to have substantial role in propagation mechanism of such detonations. In regular detonations, the lead shock ignites all the gases passing through it, hence, the transverse waves and hydrodynamic instabilities do not play crucial role in propagation mechanism of such regular detonations. In comparison with previous numerical simulations present simulation using single-step kinetics shows a distinct keystone-shaped region at the end of the detonation cell.

Mahmoudi, Y.; Mazaheri, K.; Parvar, S.

2013-10-01

72

Simulations of detonation wave propagation in rectangular ducts using a three-dimensional WENO scheme  

SciTech Connect

This paper reports high resolution simulations using a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third-order TVD Runge-Kutta time stepping method to examine the features of detonation front and physics in square ducts. The simulations suggest that two and three-dimensional detonation wave front formations are greatly enhanced by the presence of transverse waves. The motion of transverse waves generates triple points (zones of high pressure and large velocity coupled together), which cause the detonation front to become locally overdriven and thus form ''hot spots.'' The transversal motion of these hot spots maintains the detonation to continuously occur along the whole front in two and three dimensions. The present simulations indicate that the influence of the transverse waves on detonation is more profound in three dimensions and the pattern of quasi-steady detonation fronts also depends on the duct size. For a ''narrow'' duct (4L x 4L where L is the half-reaction length), the detonation front displays a distinctive ''spinning'' motion about the axial direction with a well-defined period. For a wider duct (20L x 20L), the detonation front exhibits a ''rectangular mode'' periodically, with the front displaying ''convex'' and ''concave'' shapes one following the other and the transverse waves on the four walls being partly out-of-phase with each other. (author)

Dou, Hua-Shu; Tsai, Her Mann [Temasek Laboratories, National University of Singapore (Singapore); Khoo, Boo Cheong; Qiu, Jianxian [Department of Mechanical Engineering, National University of Singapore (Singapore)

2008-09-15

73

Stationary and Nonstationary Wave Structures that Arise in Stabilization of Detonation Over a Compression Surface  

Microsoft Academic Search

The paper reports results of numerical simulations of flow structures with oblique detonation waves that arise in supersonic flow of a uniformly mixed mixture of hydrogen with air over two–dimensional compression surfaces (wedge and cone). In the first series of calculations, the internal structure of the detonation front was not resolved but the physical processes in the remaining flow region

A. T. Berlyand; V. V. Vlasenko; S. V. Svishchev

2001-01-01

74

Calculation of Chemical Detonation Waves With Hydrodynamics and Thermochemical Equation of State  

SciTech Connect

We model detonation waves for solid explosives, using 2-D Arbitrary Lagrange Eulerian (ALE) hydrodynamics, with an equation of state (EOS) based on thermochemical equilibrium, coupled with simple kinetic rate laws for a few reactants. The EOS for the product species is based on either a BKWC EOS or on an exponential-6 potential model, whose parameters are fitted to a wide range of shock Hugoniot and static compression data. We show some results for the non ideal explosive, urea nitrate. Such a model is a powerful tool for studying such processes as initiation, detonation wave propagation and detonation wave propagation as a function of cylindrical radius.

Howard, W M; Fried, L E; Souers, P C; Vitello, P A

2001-08-01

75

A double-front structure of detonation wave as the result of phase transitions  

NASA Astrophysics Data System (ADS)

Using thermochemical code calculations, we show that the nanographite nanodiamond phase transition, which may occur in the detonation products of a number of carbon containing explosives, can affect the detonation properties and can cause a specific detonation regime with some unusual peculiarities. Among them, we first note the failure of the Chapman Jouguet condition and the presence of the sonic plane, where the Mach number is equal to unity, in a detonation product expansion wave at a lower pressure than that at the Chapman Jouguet point. The peculiarities of this detonation regime are demonstrated by the example of TNT, HNS, and RDX. The computed detonation velocities are in excellent agreement with experiments over a wide range of initial charge densities for all of the investigated explosives. The results of this work allow one to explain, e.g., contradictory experimental data on the detonation pressure and on the length of the reaction zone for TNT. We believe that some other solid solid, solid liquid, and liquid liquid phase transformations in the detonation products may also cause a detonation regime with the same features as shown here for the nanographite nanodiamond transition. We suggest a computational study that should facilitate proposing detonation experiments strongly arguing in favor of the model presented.

Victorov, Sergey B.; Gubin, Sergey A.

2006-06-01

76

Instrumentation techniques for monitoring shock and detonation waves  

SciTech Connect

CORRTEX (Continuous Reflectometry for Radius Versus Time Experiments), SLIFER (Shorted Location Indication by Frequency of Electrical Resonance), and pin probes were used to monitor several conditions of blasting such as the detonation velocity of the explosive, the functioning of the stemming column confining the explosive, and rock mass motion. CORRTEX is a passive device that employs time-domain reflectometry to interrogate the two-way transit time of a coaxial cable. SLIFER is an active device that monitors the changing frequency resulting from a change in length of a coaxial cable forming an element of an oscillator circuit. Pin probes in this application consist of RG-174 coaxial cables, each with an open circuit, placed at several known locations within the material. Each cable is connected to a pulse-forming network and a voltage source. When the cables are shorted by the advancing wave, time-distance data are produced from which a velocity can be computed. This paper describes each technique, installation of the gauge, examples of the signals, and interpretation of the records. 11 refs., 11 figs.

Dick, R.D.; Parrish, R.L.

1985-01-01

77

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

78

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

79

Thermonuclear detonation  

Microsoft Academic Search

The characteristics of, and energy transfer mechanisms involved in, thermonuclear detonation are discussed. What makes the fundamental difference between thermonuclear and chemical detonation is that the former has a high specific energy release and can therefore be employed for preliminarily compressing the thermonuclear mixture ahead of the burning wave. Consequently, with moderate (megajoule) initiation energies, a steady-state detonation laboratory experiment

L P Feoktistov

1998-01-01

80

Accurate Simulation of Multi-Dimensional Detonation Waves in a Shock-Attached Frame  

NASA Astrophysics Data System (ADS)

Numerical simulation of detonation waves is a challenging problem due to resolution requirements necessary to compute highly nonlinear multiple-scale dynamics of the shock--reaction zone structure. Widely used shock-capturing techniques are often inadequate when dealing with unstable detonations. Large errors at the lead shock propagate into the reaction zone, amplify, and can dominate the true dynamics of the detonation instability. In order to eliminate the shock-capturing errors at the lead shock, we propose a shock fitting algorithm that is based on numerical integration of the reactive Euler equations in the frame attached to the lead shock. A local system of hyperbolic partial differential equations on the shock coupled to the Euler equations inside the reaction zone is derived and used as part of a numerical algorithm. With high-order time- and space discretizations, we compute the growth of linear instability into non-linear cellular detonation waves. For the first time, we performed detailed verification of the results of detonation stability theory in two dimensions. Our approach is ideally suited for testing detonation stability theories as well as nonlinear asymptotic theories such as detonation shock dynamics.

Kasimov, Aslan

2008-11-01

81

Simulation of a nuclear blast wave with a gaseous detonation tube. Technical report  

SciTech Connect

There is an ongoing interest in simulating nonideal blast environments for nuclear effects research. In particular, one would like to be able to impose peaked blast waves on real ground surfaces and experimentally measure the ensuing dusty airblast environment. Proposed here is a gaseous detonation tube blast simulator. A disposable (or reusable) shock tube would be constructed on a in-situ ground surface of interest. The tube would be sealed and filled with a detonatable gas mixture. When a planar detonation wave is initiated at one end of the tube, it induces a peaked blast wave which expands self-similarly with time--the longer the detonation run distance, the longer the blast wave duration. Similarity analysis of such a wave (which consists of a constant-velocity Chapman-Jouguet detonation followed by an adiabatic rarefaction wave expressed in terms of a Riemann characteristic) results in a closed-form analytic solution for the flow field time history. It is shown that the static and dynamic pressure waveforms associated with this detonation give a high fidelity simulation of a nuclear surface burst.

Kuhl, A.L.

1983-03-01

82

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

83

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

Microsoft Academic Search

A hyperbolic multiphase flow model with a single pressure and a single velocity but several temperatures is proposed to deal\\u000a with the detonation dynamics of condensed energetic materials. Temperature non-equilibrium effects are mandatory in order\\u000a to deal with wave propagation (shocks, detonations) in heterogeneous mixtures. The model is obtained as the asymptotic limit\\u000a of a total non-equilibrium multiphase flow model

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

2009-01-01

84

Reactive Flow Modeling of the Interaction of TATB Detonation Waves with Inert Materials  

SciTech Connect

The Ignition & Growth model for the shock initiation and detonation of solid explosives is applied to calculating the main features of detonation waves in the triaminotrinitrobenzene (TATB) based high explosives LX-17, PBX 9502 and EDC-35. Under detonation conditions, TATB based explosives exhibit reaction zone lengths of 2 to 3 mm depending on the interactions between the detonation wave and the surrounding inert materials. This paper describes comparisons of Ignition & Growth calculations with data from several two- and three-dimensional experiments in which various materials are used to confine the TATB based explosives. The calculated unconfined failure diameters of PBX 9502 are normalized to the measured values at five initial temperatures. Failure diameters for LX-17 are then estimated by changing only the fraction ignited near the shock front. Fabry-Perot data on spherically divergent LX-17 snowball experiments is also compared to calculations. Calculated detonation velocities, wave front curvatures, and metal acceleration velocities are compared to experimental detonation data for TATB-based high explosives in tantalum, copper, PMMA, brass, and beryllium confinement. Three-dimensional prism failure test results on PBX 9502 are also stimulated using the ALE3D code.

Tarver, C M; McGuire, E M

2002-07-01

85

Theory of instability and nonlinear evolution of self-sustained detonation waves  

NASA Astrophysics Data System (ADS)

Linear stability properties and nonlinear dynamics of self-sustained detonations is investigated by means of asymptotic analysis and numerical simulations. The normal-mode linear stability analysis is carried out for gaseous detonations propagating in cylindrical tubes. By comparison of the stability predictions with experiments, it is shown that the instability plays a fundamental role in the onset of spin detonation. We derive far-field closure conditions for unsteady and multi-dimensional detonation waves in arbitrary explosive media as intrinsic properties of the reactive Euler equations in the embedded sonic surface, which is a characteristic surface. The conditions generalize previously known sonic conditions for self-sustained detonations. We investigate the nature of the sonic conditions numerically with a new numerical technique for solving the Euler equations and demonstrate that the sonic locus is a characteristic surface and an information boundary that isolates the reaction zone from the far-field flow. Starting with the general formulation, we derive an asymptotic evolution equation for self-sustained detonations in the limits of slow-time variation and weak curvature and find that the equation predicts ignition and failure of detonations. Based on the evolution equation, we formulate a theory of direct initiation of gaseous detonation that can predict critical conditions from first principles. The ignition theory is also extended to explosives with arbitrary equation of state. With the general conditions at the sonic locus available, we formulate the stability problem for high-explosive detonations described by non-ideal equation of state and calculate stability characteristics of detonation in PBX-9502 and nitromethane.

Kasimov, Aslan R.

86

Particle response to shock waves in solids: dynamic witness plate/PIV method for detonations  

NASA Astrophysics Data System (ADS)

Studies using transparent, polymeric witness plates consisting of polydimethlysiloxane (PDMS) have been conducted to measure the output of exploding bridge wire (EBW) detonators and exploding foil initiators (EFI). Polymeric witness plates are utilized to alleviate particle response issues that arise in gaseous flow fields containing shock waves and to allow measurements of shock-induced material velocities to be made using particle image velocimetry (PIV). Quantitative comparisons of velocity profiles across the shock waves in air and in PDMS demonstrate the improved response achieved by the dynamic witness plate method. Schlieren photographs complement the analysis through direct visualization of detonator-induced shock waves in the witness plates.

Murphy, Michael J.; Adrian, Ronald J.

2007-08-01

87

1899-1909: the Key Years of the Understanding of Shock Wave and Detonation Physics  

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. In 1899, Chapman provided the basis of what is called now the Chapman-Jouguet theory. During the following years, several authors (Jouguet, Hadamard, Crussard, Duhem, Dixon and the Hungarian Zemplen...) yielded important contributions to the understanding of shock wave and detonation propagation: sonicity properties, possibility of the rarefaction shock, real waves with finite thickness, real geometries and real materials, thermodynamic properties, etc... These years finished in 1909 with Duhem's paper which gathered some properties concerning real materials.

Heuzé, Olivier

2009-12-01

88

Experiments and modeling of the deposition of nano-structured alumina–titania coatings by detonation waves  

Microsoft Academic Search

Deposition of nano-structured alumina–titania coatings by detonation waves has been studied experimentally. Experiments involved entrainment of conventional (Metco 130) and nano-structured\\/agglomerated alumina–titania powders with particle size distributions between 10 and 120 ?m into the convective flow behind detonation waves. Stoichiometric mixtures of acetylene–oxygen was utilized in these experiments. Small quantities of powder (0.8–1.2 g) were placed in the detonation tube

Sergey Y Semenov; Baki M Cetegen

2002-01-01

89

Structure of the detonation wave front in a mixture of nitromethane with acetone  

NASA Astrophysics Data System (ADS)

It is shown that the leading front of an inhomogeneous detonation wave is a shock wave in which wave structures of the type of triple shock configurations are moving. It was experimentally found that the reaction in these inhomogeneities occurs in oblique shock waves. The reaction sites at the wave front are ring-shaped. In a 75: 25 mixture of nitromethane with acetone, up to 70% of the front surface is occupied by the reaction at the sites in the wave front. Measurements of the mass velocity profile indicate that afterburning takes place in the unloading area behind the Jouguet plane. Calculations of the heat release in the reaction mixture with a decrease in the mass velocity indicate that the material that have not reacted in the inhomogeneities can be ignited in the induction zone. It is suggested that the adiabatic flashes are a mechanism that generates inhomogeneities in the detonation wave front.

Buravova, S. N.

2012-09-01

90

Calculation of Chemical Detonation Waves with Hydrodynamics and a Thermochemical Equation of State  

NASA Astrophysics Data System (ADS)

We model detonation waves for solid explosives, using 2-D Arbitrary Lagrange Eulerian (ALE) hydrodynamics, with an equation of state (EOS) based on thermochemical equilibrium, coupled with simple kinetic rate laws for a few reactants. The EOS for the product species is based on an exponential-6 potential model, whose parameters are fitted to a wide range of shock Hugoniot and static compression data. We show some results for the non-ideal explosive, urea nitrate. Such a model is a powerful tool for studying such processes as initiation, and detonation wave propagation as a function of cylindrical radius.

Howard, W. M.; Fried, L. E.; Souers, P. C.; Vitello, P. A.

2002-07-01

91

Numerical computation of two-dimensional unsteady detonation waves in high energy solids  

SciTech Connect

We are concerned with theoretical modelling of unsteady, two- dimensional detonation waves in high energy solids. A mathematical model and a numerical method to solve the associated hyperbolic system of equations are presented. The model consists of the Euler equations augmented by extra conservation laws and source terms to account for chemical reaction and tracking of materials. Both the thermodynamics and the chemistry are treated in a simple way. Using a detonation analogue due to Fickett, we test several numerical methods and assess their performance in modelling the essential features of detonation waves. The numerical method selected for the full model is an extension of the conservative, shock capturing technique of Roe, together with an adaptive mesh refinement procedure that allows the resolution of fine features such as reaction zones. Results for some typical tests problems are presented. 31 refs., 23 figs., 2 tabs.

Clarke, J.F.; Karni, S.; Quirk, J.J.; Roe, P.L.; Simmonds, L.G.; Toro, E.F. (College of Aeronautics, Cranfield (United Kingdom))

1993-06-01

92

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

93

Particle response to shock waves in solids: dynamic witness plate\\/PIV method for detonations  

Microsoft Academic Search

Studies using transparent, polymeric witness plates consisting of polydimethlysiloxane (PDMS) have been conducted to measure the output of exploding bridge wire (EBW) detonators and exploding foil initiators (EFI). Polymeric witness plates are utilized to alleviate particle response issues that arise in gaseous flow fields containing shock waves and to allow measurements of shock-induced material velocities to be made using particle

Michael J. Murphy; Ronald J. Adrian

2007-01-01

94

Simulation of a nuclear blast wave with a gaseous detonation tube. Technical report  

Microsoft Academic Search

There is an ongoing interest in simulating nonideal blast environments for nuclear effects research. In particular, one would like to be able to impose peaked blast waves on real ground surfaces and experimentally measure the ensuing dusty airblast environment. Proposed here is a gaseous detonation tube blast simulator. A disposable (or reusable) shock tube would be constructed on a in-situ

Kuhl

1983-01-01

95

Numerical prediction of oblique detonation wave structures using detailed and reduced reaction mechanisms  

Microsoft Academic Search

Modelling of the structure and the limiting flow turning angles of an oblique detonation wave, established by a two-dimensional wedge, requires the implementation of detailed chemical kinetic models involving a large number of chemical species. In this paper, a method of reducing the computational effort involved in simulating such high-speed reacting flows by implementing a systematically reduced reaction mechanism is

A. A. Thaker; H. K. Chelliah

1997-01-01

96

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

97

Oblique shock wave calculations for detonation waves in brass confined and bare PBXN-111 cylindrical charges  

SciTech Connect

Shock polar theory is used to calculate the angles detonation fronts make with the cylinder wall for brass cased and bare PBXN-111 cylinders. Two extrapolated unreacted PBXN-111 Hugoniot curves are used to calculate these angles. Measured and calculated angles for bare PBXN-111 cylinders are in good agreement for one of the unreacted PBXN-111 Hugoniots. Except for the 100 mm diameter charge, the differences between calculated and measured angles for brass cased charges are beyond experimental error. Limited data suggests that the wave front curvature exhibits a large change right at the brass wall and the resolution in the experiments may not be fine enough to show it clearly. {copyright} {ital 1998 American Institute of Physics.}

Lemar, E.R. [Naval Surface Warfare Center, Indian Head Division, Indian Head, Maryland 20640 (United States); Forbes, J.W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Cowperthwaite, M. [Enig Associates, Inc., Silver Spring, Maryland 20904 (United States)

1998-07-01

98

Shock-Wave and Detonation Studies at ITEP-TWAC Proton Radiography Facility  

NASA Astrophysics Data System (ADS)

In recent years studies of shock and detonation wave phenomena at extreme dynamic conditions were performed at proton radiography facility developed at the 800 MeV proton beam line of ITEP Terawatt Accelerator (ITEP-TWAC). The facility provides a multi-frame imaging capability at 50 ?m spatial and 70 ns temporal resolution. The results of latest studies conducted there are presented, including explosion and detonation of pressed and emulsion high explosives, shock-induced dense non-ideal plasma of argon and xenon and shock loading of non-uniform metal surfaces. New compact explosive generators developed specifically for a use at proton radiography facilities are also presented.

Kolesnikov, Sergey; Dudin, Sergey; Lavrov, Vladimir; Nikolaev, Dmitry; Mintsev, Victor; Shilkin, Nikolay; Ternovoi, Vladimir; Utkin, Alexander; Yakushev, Vladislav; Yuriev, Denis; Fortov, Vladimir; Golubev, Alexander; Kantsyrev, Alexey; Shestov, Lev; Smirnov, Gennady; Turtikov, Vladimir; Sharkov, Boris; Burtsev, Vasily; Zavialov, Nikolay; Kartanov, Sergey; Mikhailov, Anatoly; Rudnev, Alexey; Tatsenko, Mikhail; Zhernokletov, Mikhail

2011-06-01

99

The propagation of detonation waves in non-ideal condensed-phase explosives confined by high sound-speed materials  

NASA Astrophysics Data System (ADS)

Highly non-ideal condensed-phase explosives used by the mining industry have a strong detonation velocity dependence on the charge dimension. Detonation velocities can be as low as one third of the theoretically calculated ideal detonation velocity in charge radii close to the failure radius. Under these detonation conditions the flow in the confiner can become subsonic, a flow condition under which classical shock-polar analysis is not applicable. This restriction prohibits the use of popular engineering models like detonation shock dynamics and Wood-Kirkwood type models under these confinement conditions. In addition, it has been found in the literature that subsonic flow in the confiner will increase the influence of the confining material on the detonation performance. In this work, we use a multi-phase model coupled to an elastic-plastic model (for the representation of a confiner) to explore the interaction of detonations under these confiner conditions. An ammonium nitrate based mining emulsion is investigated in aluminium and steel confinement of finite and infinite thickness representing the confiner as either a fluid or an elastic-plastic material. It is found that the presence of elastic waves is negligible close to ideal detonation conditions, but is important close to the failure radius and in detonation conditions with subsonic flow in the confiner. High sound-speed confiners support the detonation through energy transport ahead of the detonation front if desensitisation effects are negligible. The detonation front profiles are found to remain convex even in the most non-ideal detonation conditions, and the detonation front curvature only becomes concave in a localised region close to the confiner edge.

Schoch, Stefan; Nikiforakis, Nikolaos; Lee, Bok Jik

2013-08-01

100

Experimental measurements of the detonation wave profile in a TATB based explosive  

NASA Astrophysics Data System (ADS)

We report results of the experimental measurements of the detonation wave profile of the TATB based plastic bonded explosive T2 (97 w. % of TATB) using VISAR and Heterodyne Velocimetry (HV - same as Photon Doppler Velocimetry). The experiment consists in initiating a detonation wave in a 15 mm diameter cylinder of explosive using an explosive wire detonator and an explosive booster. In order to obtain the particle velocity history in the reaction zone, we measure particle velocity at the interaction of the detonation front with an aluminized window or the free surface velocity of a metallic foil. Lithium Fluoride (LIF), PMMA and steel have been tested. Several shots have been performed for different lengths of explosive. We compare the VISAR and HV measurements. With LIF and steel, VISAR and HV diagnostics give very similar profiles. The ZND profile obtained on LIF is resolved with both techniques. With PMMA, HV gives a more accurate profile than VISAR in the reaction zone. There is no evidence of the influence of the explosive cylinder length.

Bouyer, V.; Doucet, M.; Decaris, L.

101

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

102

Particle response to shock waves in solids: dynamic witness plate\\/PIV method for detonations  

Microsoft Academic Search

Studies using transparent, polymeric witness plates consisting of polydimethlysiloxane (PDMS) have been conducted to measure\\u000a the output of exploding bridge wire (EBW) detonators and exploding foil initiators (EFI). Polymeric witness plates are utilized\\u000a to alleviate particle response issues that arise in gaseous flow fields containing shock waves and to allow measurements of\\u000a shock-induced material velocities to be made using particle

Michael J. Murphy; Ronald J. Adrian

2007-01-01

103

Microwave interferometer for shock wave, detonation, and material motion measurements  

SciTech Connect

A microwave interferometer system which provides a continuous measurement of the position of interfaces, such as shock fronts, detonation fronts, or material surfaces, has been developed. The use of low-mass microcoaxial cable, some of which is commercially available, and stripline for conducting the microwave signal into the interior of an experiment makes the perturbation of the measuring system on the experiment small. Other microwave systems have measured the time of peak amplitude of a reflected signal, but the present system with proper matching produces a continuous record of position as a function of time. It is believed that this technique can be used to replace most uses of electrical contact or fiber-optic pins in high-explosive experiments. The amount of data far exceeds that which it is possible to obtain from pins or optical fibers. The matching of the microcoax to the microwave generator has an important effect on the accuracy of the technique. The effect of matching on accuracy will be described in detail, and matching methods will be discussed. A position accuracy of 0.2 mm has been attained. Several methods for extracting position information as a function of time are possible. These techniques are discussed, and their application to the analysis of an experiment is demonstrated. The data from the interferometer system is compared to a streak camera record in a phased, shock-breakout experiment. Agreement is quite good, and the superiority of this method over the pin method is demonstrated by comparing details of the streak and interferometer records.

McCall, G.H.; Bongianni, W.L.; Miranda, G.A.

1985-08-01

104

Pulse Detonation Engine Test Bed Developed.  

National Technical Information Service (NTIS)

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 Combusti...

K. J. Breisacher

2002-01-01

105

On the dynamics and linear stability of one-dimensional steady detonation waves  

NASA Astrophysics Data System (ADS)

A detailed analysis of the dynamics and linear stability of a steady one-dimensional detonation wave propagating in a binary reactive system with an Arrhenius chemical kinetics of type A+A \\rightleftharpoons B + B is carried out. Starting from the frame of the kinetic theory, the binary reactive mixture is modelled at the mesoscopic scale by the reactive Boltzmann equation (BE), assuming hard sphere cross sections for elastic collisions and step cross sections with activation energy for reactive interactions. The corresponding hydrodynamic limit is based on a second-order non-equilibrium solution of the BE obtained in a previous paper, using the Chapman-Enskog method in a chemical regime for which the reactive interactions are less frequent than the elastic collisions. The resulting hydrodynamic governing equations are the reactive Euler equations, including a rate law which exhibits an explicit dependence on the reaction heat and forward activation energy of the chemical reaction. These equations are used to describe the spatial structure of the steady detonation wave solution and investigate how this structure varies with the reaction heat. The response of the steady solution to one-dimensional disturbances is studied using a normal-mode linear approach which leads to an initial-value problem for the state variable disturbances in the reaction zone. The stability problem is treated numerically, using an iterative shooting technique to determine the unstable modes. The analysis developed here emphasizes the influence of the chemical reaction heat and activation energy on the linear stability spectra.

Carvalho, Filipe; Jacinta Soares, Ana

2012-06-01

106

The polymorphic detonation  

Microsoft Academic Search

A simple thermodynamic system, having a single first-order phase transformation, is examined as an elementary explosive. The energy needed to support self-sustaining waves is stored in the volume change of the phase transformation. It is shown that this system can support the conventional viscous detonations as well as a set of unsteady eigenvalue detonations. Eigenvalue detonations have been discussed previously

R. L. Rabie; G. R. Fowles; W. Fickett

1979-01-01

107

Shock wave physics and detonation physics --- a stimulus for the emergence of numerous new branches in science and engineering  

Microsoft Academic Search

In the period of the Cold War (1945-1991), Shock Wave Physics and Detonation Physics (SWP&DP) --- until the beginning of WWII mostly confined to gas dynamics, high-speed aerodynamics, and military technology (such as aero- and terminal ballistics, armor construction, chemical explosions, supersonic gun, and other firearms developments) --- quickly developed into a large interdisciplinary field by its own. This rapid

Peter O. K. Krehl

2011-01-01

108

A virtual test facility for the efficient simulation of solid material response under strong shock and detonation wave loading  

Microsoft Academic Search

A virtual test facility (VTF) for studying the three-dimensional dynamic response of solid materials subject to strong shock and detonation waves has been constructed as part of the research program of the Center for Simulating the Dynamic Response of Materials at the California Institute of Technology. The compressible fluid flow is simulated with a Carte- sian finite volume method and

Ralf Deiterding; Raul Radovitzky; Sean P. Mauch; Ludovic Noels; Julian C. Cummings; Daniel I. Meiron

2006-01-01

109

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

110

Theory of instability and nonlinear evolution of self-sustained detonation waves  

Microsoft Academic Search

Linear stability properties and nonlinear dynamics of self-sustained detonations is investigated by means of asymptotic analysis and numerical simulations. The normal-mode linear stability analysis is carried out for gaseous detonations propagating in cylindrical tubes. By comparison of the stability predictions with experiments, it is shown that the instability plays a fundamental role in the onset of spin detonation. We derive

Aslan R. Kasimov

2004-01-01

111

Structural studies of ceramics based on detonation-wave-treated graphite-like boron nitride  

SciTech Connect

The formation of a structure during pressureless sintering of graphite-like boron nitride (BN) powders pretreated in detonation waves was studied. The treated powders contained 10-12% wurtzite BN phase and 2-3% sphalerite phase. During sintering at just 1200{degrees}C a reverse transformation from dense BN phases to graphite-like phases and primary recrystallization of highly fragmented BN{sub g} occur as a result of the pretreatment. Accretive recrystallization of BN{sub g} begins at 1500{degrees}C and at T = 1700-1950{degrees}C platy grains with a size of 1-3 {mu}m are formed in the developed surface. At 1700{degrees}C the density of the specimens reach 0.95 of the theoretical value. The specimens produced at 1950{degrees}C have a higher compressive strength and radiation resistance than do those made without pretreatment.

Savvakin, G.I.; Dubovik, T.V.; Oleinik, G.S. [Inst. of Materials Science, Kiev (Ukraine)

1995-11-01

112

Burn front and reflected shock wave visualization in an inertially confined detonation of high explosive  

NASA Astrophysics Data System (ADS)

Proton radiography was used to investigate the spatiotemporal evolution of the burn front and associated reflected shocks on a PBX-9502 charge confined between an outer cylindrical steel liner and an inner elliptical tin liner. The charge was initiated with a PBX-9501 booster and a line wave generator at 30° from the major axis of the ellipse. This configuration provides a large region where the high explosive (HE) is not within the line of sight of the detonation line and thus offers a suitable experimental platform to test various burn models and EOS formulations. In addition, the offaxis initiation allows for the burn fronts to travel around the charge through different confining paths. Simulations with the hydrocode PAGOSA were performed to assess the accuracy of several HE burn methodologies.

Terrones, Guillermo; Burkett, Michael W.; Morris, Christopher L.

2012-03-01

113

DSD technology: A detonation reactive Huygens code.  

National Technical Information Service (NTIS)

The length of the reaction zone strongly influences the speed of propagation of detonation in multidimensional explosive pieces. Detonation Shock Dynamics (DSD) properly accounts for these effects in detonation wave-spreading problems when the radius of c...

J. Bdzil W. Fickett

1992-01-01

114

Temperaturmessung in Sphaerisch Konvergierenden Detonationswellen. Experimentelle Ergebnisse in der 800 mm-Apparatur (Temperature Measurement in Spherically Conveying Detonation Waves. Experimental Results with an 800 mm Apparatus).  

National Technical Information Service (NTIS)

The gas temperature in spherically converging detonation waves in a stoichiometric propane-oxygen mixture in a hemisphere of inner diameter 800 mm was spectroscopically investigated. For the temperature measurement 5% Ar was added to the mixture and the i...

K. Terao

1985-01-01

115

Spinning Detonation in Nitroglycerin.  

National Technical Information Service (NTIS)

A model for initiation and propagation of low-velocity detonation in nitroglycerin is proposed and discussed. It assumes interaction of incident and reflected shock waves and, under certain conditions, formation of Mach waves--locations of high pressures ...

M. F. Zimmer

1968-01-01

116

Shock wave physics and detonation physics — a stimulus for the emergence of numerous new branches in science and engineering  

Microsoft Academic Search

In the period of the Cold War (1945?1991), Shock Wave Physics and Detonation Physics\\u000a (SWP&DP) — until the beginning of WWII mostly confined to gas dynamics, high-speed\\u000a aerodynamics, and military technology (such as aero- and terminal ballistics, armor\\u000a construction, chemical explosions, supersonic gun, and other firearms developments) —\\u000a quickly developed into a large interdisciplinary field by its own. This rapid

Peter O. K. Krehl

2011-01-01

117

Parallel computing of non-ideal 3-D space detonation wave propagation with CC-NUMA system  

Microsoft Academic Search

Investigations into the parallel computing of non-ideal 3D space detonation wave propagation are presented on a high-performance computer based on CC-NUMA architecture. Upon analyzing and testing the previous serial program, the computation of curvature, first-order and second-order difference were determined to be the main objects of parallelization. Processing techniques were applied to convert the serial program into a parallel program,

Huang Qingnan; Zhong Ming

2002-01-01

118

Parallel Adaptive Simulation of Weak and Strong Transverse-Wave Structures in H2-O2 Detonations  

SciTech Connect

Two- and three-dimensional simulation results are presented that investigate at great detail the temporal evolution of Mach reflection sub-structure patterns intrinsic to gaseous detonation waves. High local resolution is achieved by utilizing a distributed memory parallel shock-capturing finite volume code that employs block-structured dynamic mesh adaptation. The computational approach, the implemented parallelization strategy, and the software design are discussed.

Deiterding, Ralf [ORNL

2010-01-01

119

Dynamic behavior of lead driven by head-on detonation waves  

NASA Astrophysics Data System (ADS)

The dynamic behavior of Pb driven by head-on sweeping detonation waves is studied in comparison with the behavior of Cu and W alloy. High-speed frame photography and pulsed X-ray radiography records have shown that a jet-like spiking is formed in the collision region of Pb flyer and the length of spiking extends rapidly from mm to cm size because of the significant speed gradients of mass particles inside the spiking body. Multi-layered structures of the spiking are recorded, which reflect the details of shock wave fronts inside the flyer and the melting, fracture related parameters. The typical mass densities inside the spiking structure fixed by the pulsed X-ray radiography are evaluated as about 7%~17% of the initial density of Pb. The dynamic strength and shock melting should have played a dominant role in the initial spiking formation stage. The cavitation and fragmentation process inside the molten or near molten Pb flyer in the collision region elapse only in sub-microsecond, during which the continuum of shocked Pb turns into porous and dispersed state under intense tensional release wave and the later evolution pattern of the spiking at the late stages of experimental diagnostics is preliminarily defined. The vertical bundles in the crown-like spiking pattern caused by K-H instabilities in Pb flyer can be clearly observed under more intense loading. In the collision region of Cu and W flyer jet-like spiking is also observed, which reflects multidimensional spalling mechanism in un-melting metal with its own flow strength and fracture strength.

Zhang, Chongyu; Hu, Haibo; Tang, Tiegang; Sun, Xuelin; Zhang, Zhengtao

2012-03-01

120

Reaction Zone of Steady-State Detonation Waves in Dinitrodiazapentane and RDX  

NASA Astrophysics Data System (ADS)

The detonation waves structure of pressed high explosives (HE) dinitrodiazapentane (DNP) and RDX with different initial densities was investigated by the laser interferometric system VISAR. The experimental results are the profiles of surface velocity of foils placed at the boundary between a HE sample and a water ``window''. In DNP the Von Neumann spike was observed for all studied initial densities, and one of the most interesting features in these results is the unexpectedly large ratio (reaching two) of the von Neumann peak to C-J point parameters. Earlier it was found that in RDX with initial particle size of ~80 ?m existed the critical initial density of 1.73 g/cm3 above which the monotone increase of parameters in the reaction zone was observed. Now it is shown that in acetone-recrystallized RDX with initial particle size of ~5 ?m this critical density is much lower (~1.30-1.35 g/cm3). Above this density the Von Neumann spike was observed. The experimental results are explained by chemical reaction in the shock front and influence of initial density, particle sizes and preparation conditions of samples on the efficiency of the ``hot spots'' and thus on the rate of this reaction.

Kolesnikov, Sergey A.; Utkin, Alexander V.; Ananin, Alexander V.; Pershin, Sergey V.; Fortov, Vladimir E.

2004-07-01

121

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

122

Influence of sweeping detonation-wave loading on shock hardening and damage evolution during spallation loading in tantalum  

NASA Astrophysics Data System (ADS)

Widespread research over the past five decades has provided a wealth of experimental data and insight concerning the shock hardening, damage evolution, and the spallation response of materials subjected to square-topped shock-wave loading profiles. However, fewer quantitative studies have been conducted on the effect of direct, in-contact, high explosive (HE)-driven Taylor wave (unsupported shocks) loading on the shock hardening, damage evolution, or spallation response of materials. Systematic studies quantifying the effect of sweeping-detonation wave loading are yet sparser. In this study, the shock hardening and spallation response of Ta is shown to be critically dependent on the peak shock stress and the shock obliquity during sweeping-detonation-wave shock loading. Sweeping-wave loading is observed to: a) yield a lower spall strength than previously documented for 1-D supported-shock-wave loading, b) exhibit increased shock hardening as a function of increasing obliquity, and c) lead to an increased incidence of deformation twin formation with increasing shock obliquity.

Gray, G. T.; Hull, L. M.; Livescu, V.; Faulkner, J. R.; Briggs, M. E.; Cerreta, E. K.

2012-08-01

123

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

124

Surface chemical reaction of laser ablated aluminum sample for detonation initiation  

SciTech Connect

We explore the evolution of metal plasma generated by high laser irradiances and its effect on the surrounding air by using shadowgraph images after laser pulse termination; hence the formation of laser supported detonation and combustion processes has been investigated. The essence of the paper is in observing initiation of chemical reaction between ablated aluminum plasma and oxygen from air by inducing high power laser pulse (>1000 mJ/pulse) and conduct a quantitative comparison of chemically reactive laser initiated waves with the classical detonation of exploding aluminum (dust) cloud in air. Findings in this work may lead to a new method of initiating detonation from metal sample in its bulk form without the need of mixing nano-particles with oxygen for initiation.

Kim, Chang-hwan; Yoh, Jack J. [School of Mechanical and Aerospace Engineering, Seoul National University, 599 Kwanakro, Kwanakgu, Seoul, Korea 151-742 (Korea, Republic of)

2011-05-01

125

Detonation Structure Simulation with AMROC  

Microsoft Academic Search

Numerical simulations can be the key to the thorough under- standing of the multi-dimensional nature of transient detonation waves. But the accurate approximation of realistic detonations is extremely de- manding, because a wide range of different scales needs to be resolved. In this paper, we summarize our successful efforts in simulating multi- dimensional detonations with detailed and highly stiff chemical

Ralf Deiterding

2005-01-01

126

Detonation Structure and Gross Properties  

Microsoft Academic Search

The effect of transverse wave structure on the overall behavior of a detonation wave is investigated theoretically using a planar mode detonation as a model. The balance conditions for a steady flow are solved numerically for a particular assumed non-ideality of the flow (as indicated by transverse wave strength) and adjusted path processes within the non-steady flow region near the

ROGER A. STREHLOW

1971-01-01

127

Fundamentals of rotating detonations  

NASA Astrophysics Data System (ADS)

A rotating detonation propagating at nearly Chapman-Jouguet velocity is numerically stabilized on a two-dimensional simple chemistry flow model. Under purely axial injection of a combustible mixture from the head end of a toroidal section of coaxial cylinders, the rotating detonation is proven to give no average angular momentum at any cross section, giving an axial flow. The detonation wavelet connected with an oblique shock wave ensuing to the downstream has a feature of unconfined detonation, causing a deficit in its propagation velocity. Due to Kelvin-Helmholtz instability existing on the interface of an injected combustible, unburnt gas pockets are formed to enter the junction between the detonation and oblique shock waves, generating strong explosions propagating to both directions. Calculated specific impulse is as high as 4,700 s.

Hishida, Manabu; Fujiwara, Toshi; Wolanski, Piotr

2009-04-01

128

Steady detonation waves via the Boltzmann equation for a reacting mixture  

Microsoft Academic Search

Abstract Based on the Boltzmann equation, the detonation problem is dealt with on am esoscopic level. The model,is based on the assumption,that ahead of a shock an explosive gas mixture is in meta stable equilibrium. Starting from the Von Neumann point the chemical reaction, initiated by the pressure jump, proceeds until the chemical equilibrium is reached. Numerical solutions of th

Fc Onforto; R Monaco; F Schurrer; I Ziegler; Dipartimento Di Matematica

129

Structure of the stationary zone and relaxation instability of a detonation wave in heterogeneous media  

Microsoft Academic Search

In the present study we consider the two-phase detonation of mixtures of a gas and condensed particles. The particles of condensate (liquid or solid particles) may be a fuel, an oxidizer, or an inert component. The gaseous phase is, respectively, an oxidizer, a fuel, or a combustible mixture. The results of an analysis of this relatively simple two-phase system can

V. A. Kopotev; N. M. Kuznetsov

1986-01-01

130

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

NASA Astrophysics Data System (ADS)

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 companion paper presents the analytical LTD airbreathing inlet and vehicle aerodynamics models used to predict basic engine performance and vehicle drag characteristics, including inlet total pressure recovery, captured air mass flow rate, ram drag, etc. - all projected vs. flight Mach number and altitude. The results of this parametric study suggest an optimum inlet air gap of 3-cm for the 100-cm diameter centerbody (external compression inlet), and that Mach 5.5 at 30-km is a reasonable choice for transitioning into the rocket mode.

Richard, Jacques C.; Myrabo, Leik N.

2005-04-01

131

Transient Model for Thermal Detonation.  

National Technical Information Service (NTIS)

A transient model for the description of vapor explosions was developed on the basis of the thermal detonation theory. The model describes the time evolution of thermal detonation waves due to the energy release within the wave. The fragmentation of the m...

K. Karachalios

1987-01-01

132

Numerical studies of pre-detonator ignition of pulse detonation engine  

NASA Astrophysics Data System (ADS)

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 role in the introduction of the detonation wave in the pre-detonator into the main tube.

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

133

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

134

Proceedings of the Zel'Dovich Memorial International Conference on Combustion, Detonation, Shock Waves Held in Moscow, Russia on 12-17 September 1994. Volume 2.  

National Technical Information Service (NTIS)

Professor Yakov Borisovich Zel'dovich was one of the most eminent scientists of the 20th century. He made outstanding contributions to the development of the modern theory of combustion and detonation, physics of explosion and shock waves, nuclear physics...

1994-01-01

135

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

136

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

137

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

138

Detonation-wave technique for on-load deposit removal from surfaces exposed to fouling; Part 1: Experimental investigation and development of the method  

SciTech Connect

The paper presents a description and results of the experimental research, development, and full-scale testing of a new technique for cleaning gas-swept surfaces exposed to fouling, such as found in boilers, furnaces, heat exchangers, reactors, and gas ducts, by means of detonation waves. Part 1 describes the principles and reports on experimental investigations and optimization of the technique. Part 2 reports on several years of experience in applying the technique in full-scale operation in two large coal-fired boilers. Experiments involved detailed measurements of the pressure wave characteristics at a laboratory-scale model of a boiler furnace at a range of operating conditions and produced necessary information for optimum design and operation of the detonation wave generator. The investigation enabled a close insight into the detonation and shock wave generation, their behavior during propagation through the connecting ducts, and attenuation in the inner space of the model furnace. A good indication has also been obtained of the wave impact and effects on deposit-removal from different packages of tube bundles, which were placed in the model boiler in order to mimic boiler heating surfaces.

Hanjalic, K. (Univ. of Erlangen-Nuernberg (Germany). Lehrstuhl fuer Stroemungsmechanik); Smajevic, I. (Univ. of Sarajevo, Bosnia (Yugoslavia))

1994-01-01

139

Bidirectional slapper detonators in spherical explosion systems  

NASA Astrophysics Data System (ADS)

A bidirectional slapper detonator has been proven effective for producing a spherically expanding shock wave. Two bridge foils are used to propel flyers in opposite directions, thereby initiating two explosive pellets, each embedded in one hemisphere of a spherical system. This detonation system produces a nearly perfect spherically expanding detonation front.

Martinez, Ernest C.

1990-11-01

140

FROM THE HISTORY OF PHYSICS: Thermonuclear detonation  

Microsoft Academic Search

The characteristics of, and energy transfer mechanisms involved in, thermonuclear detonation are discussed. What makes the fundamental difference between thermonuclear and chemical detonation is that the former has a high specific energy release and can therefore be employed for preliminarily compressing the thermonuclear mixture ahead of the burning wave. Consequently, with moderate (megajoule) initiation energies, a steady-state detonation laboratory experiment

L. P. Feoktistov

1998-01-01

141

Continuous Detonation of a Subsonic Flow of a Propellant  

Microsoft Academic Search

The principal possibility of organizing controlled combustion of a subsonic flow of a propellant in longitudinal pulsed and spin detonation waves is experimentally verified. Conditions and reasons for the existence of detonation waves are considered.

F. A. Bykovskii; E. F. Vedernikov

2003-01-01

142

Detonation-wave technique for on-load deposit removal from surfaces exposed to fouling; Part 2: Full-scale application  

SciTech Connect

The paper reports on the full-scale application and testing of the detonation-wave technique in two boilers, fired with pulverized coal, of total thermal power of 600 MW. Continuous monitoring over a period of several years confirmed earlier laboratory findings, reported in the companion Part 1 of the paper. The testing proved that the technique is efficient and reliable, with a number of advantages in comparison with various conventional cleaning methods. In spite of the fact that the lining of one of the boilers is made of classic refractory material, careful records and inspection over several years of daily application of the detonation wave technique showed no signs of any undesirable effects. The method was officially adopted as a routine deposits removal technique in the Power Plant Kakanj'' in Bosnia.

Hanjalic, K. (Univ. of Erlangen-Nuernberg (Germany)); Smajevic, I. (Univ. of Sarajevo, Bosnia (Yugoslavia))

1994-01-01

143

Reaction zone structure in supracompressed detonating explosives  

Microsoft Academic Search

Nanosecond time resolved particle velocity histories of supracompressed detonation waves in TNT-, TATB-, and HMX-based explosives are measured using a VISAR laser velocimeter and calculated using the ignition and growth reactive flow hydrodynamic computer code model. The Zeldovich-von Neumann-Doering (ZND) detonation wave structure is observed at pressures more than twice the self-sustaining detonation wave pressure. TNT and TATB exhibited a

L. G. Green; C. M. Tarver; D. J. Erskine

1989-01-01

144

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

145

DSD Technology: A detonation reactive Huygens code  

NASA Astrophysics Data System (ADS)

The length of the reaction zone strongly influences the speed of propagation of detonation in multi-dimensional explosive pieces. Detonation Shock Dynamics (DSD) properly accounts for these effects in detonation wave-spreading problems when the radius of curvature of the multi-dimensional detonation shock is large compared to the explosive's reaction-zone length. This report is a user manual for our two-dimensional implementation of this method, a FORTRAN subroutine called DSD Technology.

Bdzil, John; Fickett, Wildon

1992-07-01

146

Steady Non-Ideal Detonation  

NASA Astrophysics Data System (ADS)

Highly non-ideal explosives, such as commercial ammonium nitrate based explosives used in mining and blasting, have critical charge diameters of several centimetres and relatively low detonation speeds. Shock polar match analyses between these explosives and confining inert materials give two main types of interactions. For the first type (denoted here by case I), the detonation drives an oblique shock into the confiner. For the second type (case II), a wave propagates in the confiner ahead of the detonation wave in the explosive. In case I, numerical simulations show that for a given explosive model there is a unique relationship (valid for all charge diameters and confinements) between the velocity of detonation (VoD) and the curvature of the detonation shock at the charge axis. This relationship is shown to be well predicted by a quasi-one-dimensional analysis. A simple detonation shock dynamics method which uses this relationship predicts the VoD provided the explosive is sufficiently confined (usually the case in mining), but is inaccurate in the limit of an unconfined charge. For commercial explosives confined by rocks, a significant proportion of problems are case II. Numerical simulations are performed to investigate the coupling mechanisms in these situations. It is found that, in agreement with an approximate theory, the detonation is driven up to VoDs near the confiner's sound speed, and the wave in the confiner weakly pre-compresses the explosive ahead of the detonation front.

Sharpe, G. J.; Luheshi, M. Y.; Braithwaite, M.; Falle, S. A. E. G.

2009-12-01

147

A command procedure for presenting the parameters of the shock wave from detonating explosive charges: TRYCK  

NASA Astrophysics Data System (ADS)

A computer operating system for an interactive determination of the independant variables of shock waves in the air is described. For a given distance and charge weight, one or several shock wave variables can be obtained. For a given charge weight the variables can be found for different distances. Variables can be determined by chart plotting. Data is available for trinitotoluene, and fuel-air explosive charges.

Tollbom, B.

1983-03-01

148

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

149

Direct initiation of detonation  

Microsoft Academic Search

This study is both a theoretical and experimental investigation of the initiation of detonation by non-ideal blast waves. The theoretical portions consisted of two studies: (1) an analytic study of the flow fields associated with heat addition during the initial phases of heat addition to a source region which is chemically reactive, and (2) a study of the initiation of

R. A. Strehlow; H. O. Barthel

1977-01-01

150

Dynamic aspects of detonations; International Colloquium on Dynamics of Explosions and Reactive Systems, 13th, Nagoya, Japan, July 28-Aug. 2, 1991, Technical Papers  

NASA Astrophysics Data System (ADS)

Various papers on the dynamic aspects of detonations are presented. Individual subjects addressed include: high-resolution numerical simulations for 2D unstable detonations, simulation of cellular structure in a detonation wave, Mach reflection of detonation waves, mechanism of unstable detonation front origin, numerical modeling of galloping detonation, experimental study of the fine structure in spin detonation, influence of fluorocarbon on H2O2Ar detonation, digial signal processing analysis of soot foils, cylindrical detonations in methane-oxygen-nitrogen mixtures, structure of reaction waves behind oblique shocks, ignition in a complex Mach structure, simulations for detonation initiation behind reflected shock waves. Also discussed are: limiting tube diameter of gaseous detonation, mechanisms of detonation propagation in a porous medium propagation and extinction of detonation waves in tube bundles, structure and velocity deficit of gaseous detonation in rough tubes, possible method for quenching of a gaseous detonation, effect of hollow heterogeneities on nitromethane detonation.

Kuhl, A. L.; Leyer, J.-C.; Borisov, A. A.; Sirignano, W. A.

151

Physiological changes in pigs exposed to a blast wave from a detonating high-explosive charge.  

PubMed

The aim of this project was to study respiration, circulation, and brain activity in pigs during and after a blast wave exposure. Ten anesthetized pigs were used. Seven were exposed to blast and three were controls. Physiological parameters of respiration and circulation as well as cortical activity were followed from 30 minutes before until 120 minutes after the real or simulated blast. There were no significant changes in heart rhythm, cardiac output, arterial oxygen or carbon dioxide tension, blood pH, or mixed venous saturation during the experiment. The blast exposure caused intestinal injuries but no lung damage. A transient flattening of the electroencephalogram was seen immediately after the blast in four experimental animals, in contrast to the unchanged baseline electroencephalogram of the control animals. This momentary depression of cortical activity accompanied by short-lasting apnea indicates a blast wave-induced effect on the brainstem or higher controlling center. PMID:10709373

Axelsson, H; Hjelmqvist, H; Medin, A; Persson, J K; Suneson, A

2000-02-01

152

Gas Detonation Forming by a Mixture of H2+O2 Detonation  

Microsoft Academic Search

Explosive forming is one of the unconventional techniques in which, most commonly, the water is used as the pressure transmission medium. One of the newest methods in explosive forming is gas detonation forming which uses a normal shock wave derived of gas detonation, to form sheet metals. For this purpose a detonation is developed from the reaction of H2+O2 mixture

Morteza Khaleghi Meybodi; Hossein Bisadi

2009-01-01

153

Burning and detonation  

SciTech Connect

The effect of confined burning explosive abutting nonburning explosive in a variety of one-dimensional geometries has been studied by numerical simulation, demonstrating the effects of confinement, burning rate, and shock sensitivity. The model includes porous bed burning, compressible solids and gases, shock-induced decomposition with possible transition to detonation, and constant velocity ignition waves. Two-phase flow, gas relative to solid, is not allowed. Because the shock sensitivity of an explosive changes with explosive density and because such experimental data is rarely available over a range of densities, a method for the calculation of the density effect on the initial-shock-pressure, distance-to-detonation (wedge test) measure of shock sensitivity is given. The calculation uses the invariance with density of the shock particle velocity as a function of time to detonation, and the experimental data at some high density.

Forest, C.A.

1981-01-01

154

Transition to longitudinal instability of detonation waves is generically associated with Hopf bifurcation to time-periodic galloping solutions  

Microsoft Academic Search

We show that transition to longitudinal instability of strong detonation solutions of reactive compressible Navier--Stokes equations is generically associated with Hopf bifurcation to nearby time-periodic \\

Benjamin Texierand; Kevin Zumbrun

2008-01-01

155

Thermonuclear Detonations in Collapsing White Dwarf Stars  

Microsoft Academic Search

Collapsing white dwarf stars (or degenerate cores) may occur in binary systems, in the formation of Type I supernovae or in the formation of pulsars. These collapsing configurations may explode their nuclear fuel (12C or16O) by the detonation wave mechanism. A combination of analytical and numerical models is used to investigate the formation of detonation waves. The tentative conclusion is

J. Craig Wheeler; Carl J. Hansen

1971-01-01

156

Thermonuclear detonations in collapsing white dwarf stars  

Microsoft Academic Search

Collapsing white dwarf stars (or degenerate cores) may occur in binary systems, in the formation of Type I supernovae or in the formation of pulsars. These collapsing configurations may explode their nuclear fuel (12C or16O) by the detonation wave mechanism. A combination of analytical and numerical models is used to investigate the formation of detonation waves. The tentative conclusion is

J. Craig Wheeler; Carl J. Hansen

1971-01-01

157

Transition to Longitudinal Instability of Detonation Waves is Generically Associated with Hopf Bifurcation to Time-Periodic Galloping Solutions  

NASA Astrophysics Data System (ADS)

We show that transition to longitudinal instability of strong detonation solutions of reactive compressible Navier-Stokes equations is generically associated with Hopf bifurcation to nearby time-periodic "galloping", or "pulsating", solutions, in agreement with physical and numerical observation. In the process, we determine readily numerically verifiable stability and bifurcation conditions in terms of an associated Evans function, and obtain the first complete nonlinear stability result for strong detonations of the reacting Navier-Stokes equations, in the limit as amplitude (hence also heat release) goes to zero. The analysis is by pointwise semigroup techniques introduced by the authors and collaborators in previous works.

Texier, Benjamin; Zumbrun, Kevin

2011-02-01

158

Analysis of Laser-Generated Impulse In An Airbreathing Pulsed Detonation Engine: Part 1  

NASA Astrophysics Data System (ADS)

An investigation is performed on an airbreathing laser propulsion (LP) system designed to propel a 1.4 m diameter, 120-kg (dry mass) vehicle called the Lightcraft Technology Demonstrator (LTD) into low Earth orbit, along with its opto-electronics payload. The LTD concept led directly to the model No.200 lightcraft - recently demonstrated in laboratory and flight experiments at White Sands Missile Range, NM at the High Energy Laser Systems Test Facility (HELSTF), using the 10-kW PLVTS CO2 laser. The pulsed detonation wave engine (PDE) employs repetitively ignited, laser-supported detonation (LSD) waves to develop thrust by expanding high pressure blast waves over an annular, interior shroud surface. Numerical simulation of thruster impulse is accomplished with a 1-D cylindrical model of blast waves propagating radially outward from a laser-generated `line-source' of high temperature, high pressure air. External airflow over the LTD structure is also analyzed to predict basic engine/vehicle drag characteristics, including inlet total pressure recovery, and captured air mass flow rate - all projected vs. flight Mach number and altitude.

Richard, Jacques C.; Myrabo, Leik N.

2005-04-01

159

Detonating apparatus  

DOEpatents

1. Apparatus for detonation of high explosive in uniform timing comprising in combination, an outer case, spark gap electrodes insulatedly supported in spaced relationship within said case to form a spark gap, high explosive of the class consisting of pentaerythritol tetranitrate and trimethylene trinitramine substantially free from material sensitive to detonation by impact compressed in surrounding relation to said electrodes including said spark gap under a pressure from about 100 psi to about 500 psi, said spark gap with said compressed explosive therein requiring at least 1000 volts for sparking, and means for impressing at least 1000 volts on said spark gap.

Johnston, Lawrence H. (Minneapolis, MN)

1976-01-01

160

Spinning instability of gaseous detonations  

NASA Astrophysics Data System (ADS)

We investigate hydrodynamic instability of a steady planar detonation wave propagating in a circular tube to three-dimensional linear perturbations, using the normal mode approach. Spinning instability is identified and its relevance to the well-known spin detonation is discussed. The neutral stability curves in the plane of heat release and activation energy exhibit bifurcations from low-frequency to high-frequency spinning modes as the heat release is increased at fixed activation energy. With a simple Arrhenius model for the heat release rate, a remarkable qualitative agreement with experiment is obtained with respect to the effects of dilution, initial pressure and tube diameter on the behaviour of spin detonation. The analysis contributes to the explanation of spin detonation which has essentially been absent since the discovery of the phenomenon over seventy years ago.

Kasimov, Aslan R.; Stewart, D. Scott

2002-09-01

161

Spinning Instability of Gaseous Detonations  

NASA Astrophysics Data System (ADS)

We investigate hydrodynamic instability of a steady planar detonation wave propagating in a circular tube to three-dimensional linear perturbations, using normal-mode approach. Spinning instability is identified and its relevance to the well-known spin detonation is discussed. The neutral stability curves in the plane of heat release and activation energy exhibit bifurcations from a single-head to multiple-head spinning modes as the heat release is increased at fixed activation energy. With a simple Arrhenius model for the heat release rate a remarkable qualitative agreement with experiment is obtained with respect to the effects of dilution, initial pressure, and tube diameter on the behavior of spin detonation. The analysis contributes to explanation of the spin detonation which has been lacking since the discovery of the phenomenon over seventy years ago.

Kasimov, Aslan; Stewart, D. Scott

2001-11-01

162

Steady non-ideal detonations  

NASA Astrophysics Data System (ADS)

Theories for determining the velocity of detonation (VoD) in highly non-ideal explosives, e.g. commercial explosives used in mining, are discussed. Such explosives have critical charge diameters of several centimetres. An analysis of the interaction between detonations and confining materials along the explosive-confiner interface reveals there a two main types of interaction. In the first (denoted here by case 1) the detonation drives an oblique shock into the confiner. For the second (case 2), a wave propagates in the confiner ahead of the detonation in the explosive. Shock polar interactions are examined for commercial explosives and rocks, which shows that a significant proportion of problems are case 2 in mining. For case 1, numerical simulations show that for a given explosive model there is a unique relationship (valid for all charge diameters and confinements) between the VoD and the curvature of the detonation shock at the charge axis. This relationship is shown to be well predicted by a quasi-one-dimensional type analysis. A simple detonation shock dynamics method which uses this relationships predicts well the VoD even in highly non-ideal cases, provided the explosive is sufficiently confined (usually the case in mining), but which is inaccurate in the limit of an unconfined charge. Preliminary results of a novel variational method for solving the unconfined situation are also discussed. Numerical simulations are performed to investigate the coupling mechanisms in case 2 situations, including the influence on diameter effects. It is shown that, in agreement with an approximate theory, the detonation is driven up to VoDs above the confiner's sound speed, and the wave in the confiner weakly pre-compresses the explosive ahead of the detonation front.

Sharpe, Gary

2009-06-01

163

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

164

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

165

Two-phase steady detonation analysis  

SciTech Connect

Steady solutions to a set of two-phase reactive flow model equations are studied to test the hypothesis that observed deviations from Chapman-Jouguet (CJ) detonation states in porous solid propellants are manifestations of the two-phase nature of the flow. Shock jump relations are presented. A simple expression for a minimum detonation wave speed analogous to a CJ detonation for a single phase is given. The analogous CJ point is a sonic point. In the appropriate limit the minimum detonation velocity varies linearly with initial bulk density, and the corresponding detonation pressure varies with the square of initial bulk density. Non-ideal gas effects play an important role in determining CJ conditions. The effect of reaction zone structure is studied to determine its effect on detonation end states. 19 refs., 7 figs., 1 tab.

Powers, J.M.; Stewart, D.S.; Krier, H.

1987-01-01

166

CIT: Detonators  

Microsoft Academic Search

Detonators are: (1) exploding bridge wire (EBW) initiators, (2) exploding foil initiators (EFI), and (3) explosive surface initiators (covered under 'high explosives'). Controls are: (1) NSG DUL: 6.A.1., (2) WA: 1.A.7, (3) EU: 1A007, 3A232, and (4) HS: 3603.00. Nuclear uses are to initiate HE charge of an implosion-type nuclear weapon. Other uses are commercial mining operations (EBWs), and downhole

Davis R. Thomsen; Loretta A. Weiss

2012-01-01

167

Detonator Performance Characterization using Multi-Frame Laser Schlieren Imaging  

Microsoft Academic Search

Multi-frame Laser Schlieren Imaging of shock waves produced by detonators in transparent witness materials can be used to evaluate detonator performance. We use inverse calculations of the 2D propagation of shock waves in the EPIC finite element model computer code to calculate a temporal-spatial-pressure profile on the surface of the detonator that is consistent with the experimental shock waves from

Steven Clarke; Colin Landon; Michael Murphy; Michael Martinez; Thomas Mason; Keith Thomas

2009-01-01

168

Nonideal detonation of Al-rich emulsion explosives  

Microsoft Academic Search

It is known that emulsion explosives have non-ideally in their detonation. The behavior of the non-ideal detonation has not yet been sufficiently investigated. In order to obtain a better comprehension of the non-ideal detonation behavior, optical measurements and measurements of the velocity of the detonation wave were carried out. Streak photographs were taken by an image converter camera using an

Shigeru Itoh; Katsuhiko Takahashi; Kenji Murata; Yukio Katoh; Akio Kira; Masaki Kojima; Masahiro Fujita

1997-01-01

169

Detonation Sensitivity and Failure Diameter in Homogeneous Condensed Materials  

Microsoft Academic Search

A model is proposed for steady detonation waves in homogeneous condensed materials. The model is one in which the pressure profile in the direction of the wave motion is square between shock front and Chapman-Jouguet surface. The reaction rate in the steady zone is allowed to vary with the steady detonation wave velocity according to the temperature in the reaction

Marjorie W. Evans

1962-01-01

170

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

171

Shock Pressure Determination in Detonator Wires.  

National Technical Information Service (NTIS)

High-resolution microstreak photographs were used to record shock waves from water-immersed, exploding detonator wires. Shock velocities were read directly from the photographs, and pressures were computer from known Hugoniot data. Wires were gold or alum...

A. M. Frank G. R. Gathers

1989-01-01

172

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

173

Nonideal detonation of Al-rich emulsion explosives  

NASA Astrophysics Data System (ADS)

It is known that emulsion explosives behave non-ideally in their detonation. The behavior of the non-ideal detonation has not yet been sufficiently investigated. In order to obtain a better comprehension of the non-ideal detonation behavior, optical measurements and measurements of the velocity of the detonation wave were carried out. Streak photographs were taken by an image converter camera using a usual shadowgraph system. Five kinds of emulsion explosives which differ the aluminum contents were used in experiments. These emulsion explosives were put into copper, aluminum and PMMA containers. In case of the copper pipe container, the velocity of the detonation wave is constant at any aluminum contents. But in the case of the PMMA pipe container, the velocity of the detonation wave becomes lower in proportion to aluminum contents. The shapes of the reaction zone and the front of the detonation zone were also recognized from the streak photographs. In case of the copper pipe container, the detonation wave is plane, but in case of PMMA pipe container, the detonation wave curves near the pipe wall and its shape is a convex. It is considered that acoustic impedance of the container have effects on the propagation of the detonation wave.

Itoh, Shigeru; Takahashi, Katsuhiko; Murata, Kenji; Katoh, Yukio; Kira, Akio; Kojima, Masaki; Fujita, Masahiro

1997-12-01

174

Nonideal detonation of Al-rich emulsion explosives  

NASA Astrophysics Data System (ADS)

It is known that emulsion explosives have non-ideally in their detonation. The behavior of the non-ideal detonation has not yet been sufficiently investigated. In order to obtain a better comprehension of the non-ideal detonation behavior, optical measurements and measurements of the velocity of the detonation wave were carried out. Streak photographs were taken by an image converter camera using an usual shadowgraph system. Five kinds of emulsion explosives which differ the aluminum contents were used in experiments. These emulsion explosives were put into a copper, an aluminum and a PMMA containers. In case of the copper pipe container, the velocity of the detonation wave is constant at any aluminum contents. But in case of the PMMA pipe container, the velocity of the detonation wave becomes lower in proportion to aluminum contents. The shapes of the reaction zone and the front of the detonation zone were also recognized from the streak photographs. In case of the copper pipe container, the detonation wave is plane, but in case of PMMA pipe container, the detonation wave curves near the pipe wall and its shape is a convex. It is considered that acoustic impedance of the container have effects on the propagation of the detonation wave.

Itoh, Shigeru; Takahashi, Katsuhiko; Murata, Kenji; Katoh, Yukio; Kira, Akio; Kojima, Masaki; Fujita, Masahiro

1997-05-01

175

Detailed structure of spinning detonation in a circular tube  

SciTech Connect

A single spinning detonation wave propagating in a circular tube, discovered experimentally in 1926, is simulated three-dimensionally with a detailed chemical reaction mechanism. The detonation front obtained numerically rotates periodically with a Mach leg, whiskers, and a transverse detonation. A long pressure trail, which is distributed from the transverse detonation to downstream, was reproduced, clearly showing that the pressure trail also spins synchronously with the transverse detonation. The formation of an unburned gas pocket behind the detonation front was not observed in the present simulations because the rotating transverse detonation completely consumed the unburned gas. The calculated profiles of instantaneous OH mass fraction have a keystone shape behind the detonation front. The numerical results for pitch, track angle, Mach stem angle, and incident shock angle on the tube wall agree well with the experimental results. (author)

Tsuboi, N. [Space Transportation Engineering Department, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510 (Japan); Eto, K.; Hayashi, A.K. [Department of Mechanical Engineering, Aoyama Gakuin University, Fuchinobe 5-10-1, Sagamihara, Kanagawa 229-8558 (Japan)

2007-04-15

176

Environmentally Benign Stab Detonators  

Microsoft Academic Search

Many energetic systems can be activated via mechanical means. Percussion primers in small caliber ammunition and stab detonators used in medium caliber ammunition are just two examples. Current medium caliber (20-60mm) munitions are detonated through the use of impact sensitive stab detonators. Stab detonators are very sensitive and must be small, as to meet weight and size limitations. A mix

Gash

2005-01-01

177

Impulse generation by detonation tubes  

NASA Astrophysics Data System (ADS)

Impulse generation with gaseous detonation requires conversion of chemical energy into mechanical energy. This conversion process is well understood in rocket engines where the high pressure combustion products expand through a nozzle generating high velocity exhaust gases. The propulsion community is now focusing on advanced concepts that utilize non-traditional forms of combustion like detonation. Such a device is called a pulse detonation engine in which laboratory tests have proven that thrust can be achieved through continuous cyclic operation. Because of poor performance of straight detonation tubes compared to conventional propulsion systems and the success of using nozzles on rocket engines, the effect of nozzles on detonation tubes is being investigated. Although previous studies of detonation tube nozzles have suggested substantial benefits, up to now there has been no systematic investigations over a range of operating conditions and nozzle configurations. As a result, no models predicting the impulse when nozzles are used exist. This lack of data has severely limited the development and evaluation of models and simulations of nozzles on pulse detonation engines. The first experimental investigation measuring impulse by gaseous detonation in plain tubes and tubes with nozzles operating in varying environment pressures is presented. Converging, diverging, and converging-diverging nozzles were tested to determine the effect of divergence angle, nozzle length, and volumetric fill fraction on impulse. The largest increases in specific impulse, 72% at an environment pressure of 100 kPa and 43% at an environment pressure of 1.4 kPa, were measured with the largest diverging nozzle tested that had a 12° half angle and was 0.6 m long. Two regimes of nozzle operation that depend on the environment pressure are responsible for these increases and were first observed from these data. To augment this experimental investigation, all data in the literature regarding partially filled detonation tubes was compiled and analyzed with models investigating concepts of energy conservation and unsteady gas dynamics. A model to predict the specific impulse was developed for partially filled tubes. The role of finite chemical kinetics in detonation products was examined through numerical simulations of the flow in nonsteady expansion waves.

Cooper, Marcia Ann

178

Research into the Detonation of Ammonite PzhV-20 and Certain Other Explosives (Issledovanie Detonatsii Ammonita PzhV-20 I Nekotorykh Drugikh Vv).  

National Technical Information Service (NTIS)

Measurement of the parameters of the detonation wave (particle velocity behind the detonation front and others) constitutes an important factor in the determination of the detonation mechanism of commercial explosives. The so-called cut-off method of dete...

A. N. Dremin K. K. Shvedov V. A. Veretennikov

1969-01-01

179

Molecular dynamics simulation of spinning detonation in energetic AB material  

NASA Astrophysics Data System (ADS)

Spinning detonation-wave structure is observed in molecular dynamics simulation of a solid energetic material (EM) confined in the round tube with smooth walls. The EM is represented by a modified AB model with adjustable barrier height for exothermic reaction AB+B -> A+BB, which allows us to study the evolution of detonation-wave structure produced by instabilities of the planar detonation front as a function of physico-chemical properties of the EM material, including its thermochemistry and reactive equation of state. The planar detonation wave in a tube of relatively small radius evlolves into an unstable pulsating detonation through the development of longitudinal perturbations, which can later lead to a collapse of the detonation wave. However, as the tube radius is increased, the detonation wave structure is stabilized by a development of a single-headed spinning detonation having an unusual four-wave configuration. Further increase of the tube radius results in a multi-headed detonation structure with turbulent-like distributions of pressure and other physical variables at the front, similar to that observed in gases.

Zhakhovsky, Vasily; Budzevich, Mikalai; Landerville, Aaron; Oleynik, Ivan; White, Carter

2013-03-01

180

Modeling two-dimensional detonations with detonation shock dynamics  

SciTech Connect

In any explosive device, the chemical reaction of the explosive takes place in a thin zone just behind the shock front. The finite size of the reaction zone is responsible for: the pressure generated by the explosive being less near the boundaries, for the detonation velocity being lower near a boundary than away from it, and for the detonation velocity being lower for a divergent wave than for a plane wave. In computer models that are used for engineering design calculations, the simplest treatment of the explosive reaction zone is to ignore it completely. Most explosive modeling is still done this way. The neglected effects are small when the reaction zone is very much smaller than the explosive's physical dimensions. When the ratio of the explosive's detonation reaction-zone length to a representative system dimension is of the order of 1/100, neglecting the reaction zone is not adequate. An obvious solution is to model the reaction zone in full detail. At present, there is not sufficient computer power to do so economically. Recently we have developed an alternative to this standard approach. By transforming the governing equations to the proper intrinsic-coordinate frame, we have simplified the analysis of the two-dimensional reaction-zone problem. When the radius of curvature of the detonation shock is large compared to the reaction-zone length, the calculation of the two-dimensional reaction zone can be reduced to a sequence of one-dimensional problems. 9 refs., 5 figs.

Bdzil, J.B.; Stewart, D.S.

1988-01-01

181

Interaction between shock wave and plasma region ionized by millimeter wave beam and its application to pulse detonation system as a microwave rocket  

Microsoft Academic Search

By focusing a high-power millimeter wave beam generated by a 170GHz gyrotron, a breakdown occurred and a shock wave was driven by plasma heated by following microwave energy. The shock wave and the plasma around a focal point of a parabolic thruster were visualized by a shadowgraph method, and a transition of structures between the shock wave and the plasma

Toshikazu Yamaguchi; Reiji Komatsu; Kimiya Komurasaki; Yasuhisa Oda; Ken Kajiwara; Koji Takahashi; Keishi Sakamoto

2011-01-01

182

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

183

Detonation structures generated by multiple shocks on ram-accelerator projectiles  

Microsoft Academic Search

The detailed detonation structure generated by multiple shocks on ram-accelerator projectiles is studied using highly resolved numerical stimulations. The simulations show that the detonation structure on the projectile consists of the following basic elements: nonreactive shocks, induction regions, deflagration waves, and detonation waves. The shape and location of these basic elements strongly depends on the projectile Mach number. In some

Chiping Li; K. Kailasanath; Elaine S. Oran

1997-01-01

184

CHARACTERIZING DETONATOR OUTPUT USING DYNAMIC WITNESS PLATES  

Microsoft Academic Search

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

Michael J. Murphy; Ronald J. Adrian

2009-01-01

185

Characterizing Detonator Output Using Dynamic Witness Plates  

Microsoft Academic Search

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

Michael John Murphy; Ronald J. Adrian

2009-01-01

186

Detonation properties of the insensitive explosive TATB  

Microsoft Academic Search

The detonation properties of various compositions of the insensitive explosive TATB were investigated using thin flyer plates. These flyer plates were accelerated by electrically exploding metal foils. The divergence of the detonation wave in TATB is improved for compositions of lower-density, lower-binder-percentage, and smaller HE particle size. Increasing the velocity or the diameter of the flyer plate or increasing the

R. K. Jackson; R. C. Weingart

1976-01-01

187

Delayed detonations in full-star models of type Ia supernova explosions  

Microsoft Academic Search

Aims:We present the first full-star three-dimensional explosion simulations of thermonuclear supernovae including parameterized deflagration-to-detonation transitions that occur once the flame enters the distributed burning regime. Methods: Treating the propagation of both the deflagration and the detonation waves in a common front-tracking approach, the detonation is prevented from crossing ash regions. Results: Our criterion triggers the detonation wave at the outer

F. K. Röpke; J. C. Niemeyer

2007-01-01

188

Detonator Performance Characterization using Multi-Frame Laser Schlieren Imaging  

NASA Astrophysics Data System (ADS)

Multi-frame Laser Schlieren Imaging of shock waves produced by detonators in transparent witness materials can be used to evaluate detonator performance. We use inverse calculations of the 2D propagation of shock waves in the EPIC finite element model computer code to calculate a temporal-spatial-pressure profile on the surface of the detonator that is consistent with the experimental shock waves from the schlieren imaging. Examples of calculated 2D temporal-spatial-pressure profiles from a range of detonator types (EFI --exploding foil initiators, DOI -- direct optical initiation, EBW -- exploding bridge wire, hotwire), detonator HE materials (PETN, HMX, etc), and HE densities. Also pressure interaction profiles from the interaction of multiple shock waves will be shown. LA-UR-09-00909.

Clarke, Steven; Landon, Colin; Murphy, Michael; Martinez, Michael; Mason, Thomas; Thomas, Keith

2009-06-01

189

Methods for proving the equivalency of detonator performance  

SciTech Connect

One of the challenges facing engineers is developing newer, safer detonators that are equivalent to devices currently in use. There is no clear consensus on an exact method for drawing equivalence of detonators. This paper summarizes our current efforts to develop diagnostics addressing various aspects of detonator design to better quantify and prove equivalency. We consider various optical techniques to quantify the output pressure and output wave shape. The development of a unique interpretation of streak camera breakouts, known as the apparent center of initiation, will be discussed as a metric for detonation wave shape. Specific examples apply these techniques to the comparison of a new laser-driven detonator with an existing exploding bridgewire (EBW) detonator. Successes and short-comings of the techniques will be discussed.

Munger, Alan C [Los Alamos National Laboratory; Akinci, Adrian A [Los Alamos National Laboratory; Thomas, Keith A [Los Alamos National Laboratory; Clarke, Steve A [Los Alamos National Laboratory; Martin, Eric S [Los Alamos National Laboratory; Murphy, Michael J [Los Alamos National Laboratory

2009-01-01

190

INCOMPLETE CARBON-OXYGEN DETONATION IN TYPE Ia SUPERNOVAE  

SciTech Connect

Incomplete carbon-oxygen detonation with reactions terminating after burning of C{sup 12} in the leading C{sup 12} + C{sup 12} reaction (C-detonation) may occur in the low-density outer layers of white dwarfs exploding as Type Ia supernovae (SNe Ia). Previous studies of carbon-oxygen detonation structure and stability at low densities were performed under the assumption that the velocity of a detonation wave is derived from complete burning of carbon and oxygen to iron. In fact, at densities {rho} {<=} 10{sup 6} g cm{sup -3} the detonation in SNe Ia may release less than a half of the available nuclear energy. In this paper, we study basic properties of such detonations. We find that the length of an unsupported steady-state C-detonation is {approx_equal}30-100 times greater than previously estimated and that the decreased energy has a drastic effect on the detonation stability. In contrast to complete detonations which are one-dimensionally stable, C-detonations may be one-dimensionally unstable and propagate by periodically re-igniting themselves via spontaneous burning. The re-ignition period at {rho} {<=} 10{sup 6} g cm{sup -3} is estimated to be greater than the timescale of an SN Ia explosion. This suggests that propagation and quenching of C-detonations at these densities could be affected by the instability. Potential observational implications of this effect are discussed.

Dominguez, Inma [Departamento de Fisica Teorica y del Cosmos, University of Granada, 18071 Granada (Spain); Khokhlov, Alexei [Department of Astronomy and Astrophysics and the Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)

2011-04-01

191

Incomplete Carbon-Oxygen Detonation in Type Ia Supernovae  

NASA Astrophysics Data System (ADS)

Incomplete carbon-oxygen detonation with reactions terminating after burning of C12 in the leading C12 + C12 reaction (C-detonation) may occur in the low-density outer layers of white dwarfs exploding as Type Ia supernovae (SNe Ia). Previous studies of carbon-oxygen detonation structure and stability at low densities were performed under the assumption that the velocity of a detonation wave is derived from complete burning of carbon and oxygen to iron. In fact, at densities ? <= 106 g cm-3 the detonation in SNe Ia may release less than a half of the available nuclear energy. In this paper, we study basic properties of such detonations. We find that the length of an unsupported steady-state C-detonation is sime30-100 times greater than previously estimated and that the decreased energy has a drastic effect on the detonation stability. In contrast to complete detonations which are one-dimensionally stable, C-detonations may be one-dimensionally unstable and propagate by periodically re-igniting themselves via spontaneous burning. The re-ignition period at ? <= 106 g cm-3 is estimated to be greater than the timescale of an SN Ia explosion. This suggests that propagation and quenching of C-detonations at these densities could be affected by the instability. Potential observational implications of this effect are discussed.

Domínguez, Inma; Khokhlov, Alexei

2011-04-01

192

Rocket performance of pulse detonation engine by thermochemical theory  

Microsoft Academic Search

A model to reproduce the performance of pulse rocket engine (PDRE) by one dimensional Lagrangian hydrocode is studied by using detonation property code AISTJAN and two dimensional Eulerian hydrocode, FCEL-2D. The steady detonation propagation model by G.I. Taylor reproduce the detonation wave by the C-J isentrope gives a favorable agreement with numerical calculation with chemical reaction. Two dimensional calculation by

TANAKA Katsumi

193

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

194

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

195

On the stability of thermonuclear detonation in supernovae events  

Microsoft Academic Search

The stability of a plane stationary thermonuclear detonation in an exploding carbon white dwarf is investigated. It is shown that detonation is unstable in a wide range of densities of white dwarf matter from rho ~= 2 x 10^7 g\\/cm^3 to rho=3 x 10^9 g\\/cm^3. The detonation wave becomes stable at low densities rho = 2.1 x 10^7 g\\/cm^3. The

S. A. Kriminski; V. V. Bychkov; M. A. Liberman

1998-01-01

196

On the stability of thermonuclear detonation in supernovae events  

Microsoft Academic Search

The stability of a plane stationary thermonuclear detonation in an exploding carbon white dwarf is investigated. It is shown that detonation is unstable in a wide range of densities of white dwarf matter from ? ? 2 × 107g\\/cm3 to ? = 3 × 109g\\/cm3. The detonation wave becomes stable at low densities ? ? 107g\\/cm3 typical for a pre-expanded

S. A. Kriminski; V. V. Bychkov; M. A. Liberman

1998-01-01

197

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

198

Detonating cord stowage system  

US Patent & Trademark Office Database

A rocket-launched line charge apparatus for obstacle breaching includes at least two explosive charges connected by detonating cord. The detonating cord passes through a flexible tubing, and is bunched in a sinuous arrangement within the plastic tubing so as to store excess detonating cord. The detonating cord is attached to the two ends of the flexible tubing by cable ties. The explosive charges, the tubing and the detonating cord are enclosed in a fabric sock formed by overbraiding, the fabric sock being the strength member connecting the two explosive charges during deployment. The plastic tubing arrangement is applicable to storage of other cords in other systems involving tethered deployment of objects.

2001-12-04

199

Stability Affects of Artificial Viscosity in Detonation Modeling  

SciTech Connect

Accurate multi-dimensional modeling of detonation waves in solid HE materials is a difficult task. To treat applied problems which contain detonation waves one must consider reacting flow with a wide range of length-scales, non-linear equations of state (EOS), and material interfaces at which the detonation wave interacts with other materials. To be useful numerical models of detonation waves must be accurate, stable, and insensitive to details of the modeling such as the mesh spacing, and mesh aspect ratio for multi-dimensional simulations. Studies we have performed show that numerical simulations of detonation waves can be very sensitive to the form of the artificial viscosity term used. The artificial viscosity term is included in our ALE hydrocode to treat shock discontinuities. We show that a monotonic, second order artificial viscosity model derived from an approximate Riemann solver scheme can strongly damp unphysical oscillations in the detonation wave reaction zone, improving the detonation wave boundary wall interaction. These issues are demonstrated in 2D model simulations presented of the 'Bigplate' test. Results using LX-I 7 explosives are compared with numerical simulation results to demonstrate the affects of the artificial viscosity model.

Vitello, P; Souers, P C

2002-06-03

200

A Simplified Analysis on a Pulse Detonation Engine Model  

NASA Astrophysics Data System (ADS)

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 filling phases. The combustion and exhaust phases were theoretically analyzed with some simplifications, using the Hugoniot relation for the Chapman-Jouguet detonation wave and flow relations for self-similar rarefaction waves. Based on the simplified theoretical analysis, useful formulas for impulse density per one-cycle operation and time-averaged thrust density were derived.

Endo, Takuma; Fujiwara, Toshi

201

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

202

Maximum Entropy Theory of Non-Ideal Detonation  

Microsoft Academic Search

According to the theory of Byers Brown, in a steady state detonation the entropy production between the shock and sonic locus is a maximum in a self-sustaining wave. This has shown to hold true for all one-dimensional cases. Byers Brown also suggested a novel variational approach by maximising the global entropy generation within the detonation driving zone to solve the

Simon Watt; Martin Braithwaite; William Byers Brown; Sam Falle; Gary Sharpe

2009-01-01

203

Detonation properties of the non-ideal explosive PBXW-123  

Microsoft Academic Search

Detonation stability and wave curvature in PBXW-123, an aluminized, non-ideal explosive, have been studied. Reaction failed very slowly in unconfined 75 mm, 100 mm, and 126 mm dia. samples. Peak output pressure was still ~28 kb after a run distance of 548 mm in a 126 mm dia. charge. Confinement had a significant effect on reaction stability. Detonation velocity was

W. H. Wilson; J. W. Forbes; P. K. Gustavson; E. R. Lemar; G. T. Sutherland

1996-01-01

204

Detonation properties of the non-ideal explosive PBXW-123  

Microsoft Academic Search

Detonation stability and wave curvature in PBXW-123, an aluminized, non-ideal explosive, have been studied. Reaction failed very slowly in unconfined 75 mm, 100 mm, and 126 mm dia. samples. Peak output pressure was still ?28 kb after a run distance of 548 mm in a 126 mm dia. charge. Confinement had a significant effect on reaction stability. Detonation velocity was

W. H. Wilson; J. W. Forbes; P. K. Gustavson; E. R. Lemar; G. T. Sutherland

1996-01-01

205

Non-ideal detonation behaviour of PBX 9502  

Microsoft Academic Search

Numerical experiments are performed investigating the non-ideal detonation behaviour of PBX 9502 in two setups. In the first setup we consider a three-dimensional rate stick experiment. A booster charge initiates a reaction front leading to a curved detonation wave. The numerical results are compared to theory and experimental evidence. The effects of weak and strong confinement are discussed. The second

Stefan Schoch; Nikos Nikiforakis

2009-01-01

206

Transition of combustion to detonation in gasoline-air mixtures  

Microsoft Academic Search

The goal of the present study is to determine the time and point at which detonation develops and study the dependence of these parameters on initial mixture temperature. The experiments were performed on a test stand provided with sensors and recording equipment to determine flow rate, temperature, pressure, and composition of the mixture supplied to the detonation wave generator, the

N. N. Smirnov; A. P. Boichenko

1986-01-01

207

Detonation Initiation Techniques for Pulse Detonation Propulsion  

Microsoft Academic Search

The paper outlines recent efforts of the research team directed by the author on the development of efficient means for reducing the deflagration-to-detonation transition (DDT) run-up distance and time for liquid-fueled air-breathing Pulse Detonation Engine (PDE) applications. The main objective of the studies was to ensure fast DDT in a PDE tube at the lowest possible ignition energy, at the

S. M. Frolov

2007-01-01

208

Investigation on Novel Methods to Increase Specific Thrust in Pulse Detonation Engines via Imploding Detonations  

NASA Astrophysics Data System (ADS)

Pulse Detonation Engines (PDE) is seen to be the next generation propulsion systems due to enhanced thermodynamic efficiencies. One of the limitations in fielding practical designs has been attributed to tube diameters not exceeding 5 inches, thus affecting specific thrust. Novel methods via imploding detonations were investigated to remove such limitations. During the study, a practical computational cell size was first determined so as to capture the required physics for detonation wave propagation using a Hydrogen-Air test case. Through a grid sensitivity analysis, one-quarter of the induction length was found sufficient to capture the experimentally observed detonation wave structure. Test case models utilizing axi-symmetric head-on implosions were studied in order to understand how the implosion process reinforces a detonation wave as it expands. This in effect creates localized overdriven regions, which maintains the transition process to full detonation. A parametric study was also performed to determine the extent of diameter increase for such that practical designs could be fielded. It was found in the study that diameters of up to 12 inches could be achieved with reasonable run length distances.

Ho, Ivan

2009-11-01

209

Multiphase Detonations in Tubes  

NASA Astrophysics Data System (ADS)

There are many applications that involve shock interactions with liquid-fuel droplets and transition to detonation. Previous experimental studies have shown that the measured detonation velocity is usually significantly less than the theoretical Chapman-Jouguet (CJ) velocity in most cases and appears to depend on the size of the droplets involved. Numerical simulations have been conducted of a shock tube, where the driven section is filled with fuel droplets of various specified sizes and distributions. Gas-phase equations are solved using flux corrected transport. A Lagrangian approach is used to track the fuel droplets. Results from the simulations indicate that the observed detonation velocity in most cases is indeed less than the C-J detonation velocity. New computational diagnostics have been developed to explore the underlying physical reasons for the observed deficit in the detonation velocity. The implications of these results on the development and potential application of the Pulse Detonation Engine will also be presented.

Cheatham, Sally; Kailasanath, K.

2002-11-01

210

Surface Detonation Models of Type Ia Supernovae  

NASA Astrophysics Data System (ADS)

Flame propagation and subsequent detonation in near-Chandrasekhar mass, carbon/oxygen white dwarf stars are studied using multi-dimensional, reactive hydrodynamic simulation. The single off-center bubble ignition models studied by Townsley et al. (2007) are extended through detonation and into the homologous expansion phase. In these models, detonation occurs in a collision region at the stellar surface. Careful attention is paid to accurately calculating the yield of material burned to nuclear statistical equilibrium (NSE) and then frozen out in the expansion following the detonation wave which sweeps over the white dwarf. A self regulating process comprised of neutronization and pre-expansion leads to ˜1.1M of ^56Ni synthesized in all of the single point ignition models studied. The yield of intermediate mass elements is ˜0.1-0.3M and the explosion energies are ˜1.5x10^51 ergs, comparable to observed luminous type Ia supernovae (Ia SNe). Multi-point ignition can lead to lower luminosity explosions by releasing more energy in the deflagration which goes into expanding the white dwarf prior to detonation. A suite of pre-expanded surface detonation models are presented which have explosion energies and ^56Ni masses spanning those of observed Ia SNe. Synthetic spectra and light curves are being generated from the multi-dimensional models for more direct comparison to observed Ia SNe.

Meakin, Casey

2008-04-01

211

Spectroscopic studies of initiation and detonation chemistry  

SciTech Connect

There is much effort currently directed towards elucidating important microscopic processes in reacting high explosives (HEs). In particular, identification of early chemical steps in initiation is crucial to a better understanding of explosive sensitivity and vulnerability. The intimate coupling of the chemical work required to sustain detonation with the mechanical properties of the material and the resulting wave motion drives experimental studies to focus on realistic cases of initiation and steady-state detonation. Extrapolation of results from more homogeneous pressure and temperature domains may provide an inadequate description of the physics and chemistry involved. In practice the study of molecular properties in the extreme environment of detonation requires fast detection of transient phenomena. Over the past few years, the investigators have applied various optical techniques to studies of molecular mechanisms of initiation and detonation. The main focus has been to study reactions in compressed granular HEs like those commonly used in weapon components. Four experimental techniques were used: emission spectroscopy; fast-framing photography; time-resolved infrared spectral photography (TRISP); and single-pulse Raman spectroscopy. In this paper the investigators describe; (1) use of fast-framing photography and emission spectroscopy to study spatial and temporal character of emitted light from detonating HEs; (2) use of TRISP technique to monitor formation of water from various detonating HEs; and (3) use of single-pulse Raman scattering to study changes in shocked TATB. 11 refs., 5 figs.

Renlund, A.M.; Trott, W.M.

1987-01-01

212

Simplified modeling of transition to detonation in porous energetic materials  

SciTech Connect

A simplified model that can predict the transitions from compaction to detonation and shock to detonation is given with the aim of describing experiments in beds of porous HMX. In the case of compaction to detonation, the energy of early impact generates a slowly moving, convective-reactive deflagration that expands near the piston face and evolves in a manner that is characteristic of confined deflagration to detonation transition. A single-phase state variable theory is adopted in contrast to a two-phase axiomatic mixture theory. The ability of the porous material to compact is treated as an endothermic process. Reaction is treated as an exothermic process. The algebraic (Rankine--Hugoniot) steady wave analysis is given for inert compaction waves and steady detonation waves in a piston supported configuration, typical of the experiments carried out in porous HMX. A structure analysis of the steady compaction wave is given. Numerical simulations of deflagration to detonation are carried out for parameters that describe an HMX-like material and compared with the experiments. The simple model predicts the high density plug that is observed in the experiments and suggests that the leading front of the plug is a secondary compaction wave. A shock to detonation transition is also numerically simulated.

Stewart, D.S. (Theoretical and Applied Mechanics, University of Illinois, Urbana, Illinois 61801 (United States)); Asay, B.W. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Prasad, K. (Mechanical Engineering, Yale University, New Haven, Connecticut 06520 (United States))

1994-07-01

213

Obturator and detonation experiments in the subdetonative ram accelerator  

NASA Astrophysics Data System (ADS)

An experimental investigation has been undertaken to improve understanding of the role of the obturator and detonations in the subdetonative ram accelerator starting process. Ram accelerator start experiments were conducted with various obturator geometries to determine the obturator dynamics and assess its effect on the outcome of a start attempt. The obturator rapidly decelerates upon entrance and then moves backwards. Reversal of direction occurs more rapidly after propellant ignition, for less massive obturators, and solid geometries. Perforated geometries and decreasing obturator mass are less conducive to igniting a given propellant, as evidenced by the flowfield and start attempt outcome data presented. Wave unstarts were observed to occur with and without detonations, indicating more than one mechanism responsible for this type of start failure. Piston-initiated detonation experiments were conducted by firing the obturators without the ram accelerator projectile. The piston experiments identified the detonation limits for a wide range of propellants, but were found to not always be indicative of the upper Mach number at which a ram accelerator can be successfully started. In some instances a successful start or wave fall-off would occur at Mach numbers above which a piston alone detonated the propellant. Thus, the projectile can play a mitigating role in detonation initiation and use of piston detonation limits to quantitatively define a detonation wave unstart limit was not realized.

Schultz, E.; Knowlen, C.; Bruckner, A. P.

214

Transient Model to the Thermal Detonation.  

National Technical Information Service (NTIS)

The model calculates the escalation dynamics and the long time behavior of thermal detonation waves depending on the initial and boundary conditions (data of the premixture, ignition at a solid wall or at an open end, etc.). Especially, for a given mixtur...

K. Karachalios

1987-01-01

215

Thermonuclear Detonations in Collapsing White Dwarf Stars.  

National Technical Information Service (NTIS)

Collapsing white dwarf stars (or degenerate cores) may occur in binary systems, in the formation of Type I supernovac or in the formation of pulsars. These collapsing configurations may explode their nuclear fuel (12C or 16O) by the detonation wave mechan...

J. C. Wheeler C. J. Hansen

1970-01-01

216

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

217

Gaseous Detonations. XII. Rotational Temperatures of the Hydroxyl Free Radicals  

Microsoft Academic Search

An apparatus is briefly described which permits the photography of the ultraviolet absorption spectrum of the hydroxyl free radicals in gaseous detonation waves with a time resolution of a few microseconds. Using two mixtures, 2H2+O2 and 2H2+O2+0.075 C2H2 at 20 mm pressure, changes were studied in the absorption spectra with the progress of chemical reactions in a detonation wave. Densitometry

G. B. Kistiakowsky; F. D. Tabbutt

1959-01-01

218

Development of Pulse Detonation Engine Initiator Using Reflector for Large Bore Combustor  

NASA Astrophysics Data System (ADS)

To achieve reliable transmission of detonation wave to a pulse detonation engine (PDE) combustor, authors have proposed a PDE initiator, which consists of a predetonator and a reflector. A detonation wave propagates around the reflector changing its shape through three transition processes; from planer to cylindrical, toroidal, and planar again. Our previous study revealed that the transition to the cylindrical detonation wave upstream of the board plays a significant role in detonating hydrogen-air mixture in a 100-mm-diam-combustor. A self-sustainable condition of the cylindrical detonation wave is severe when the radius of the wave front is small. In cases using hydrogen-oxygen mixture as driver gas for the 100-mm-diam-combustor, we had to fulfill with driver gas entire upstream of the board at the critical condition for the transition to the cylindrical wave. On the other hand, curvature of the cylindrical detonation wave front becomes smaller with increasing radius of the front, so the self-sustainable condition of the cylindrical wave must be mitigated for a large bore combustor. In this study, we investigated the necessary filling diameter of the driver gas to detonate hydrogen-air cylindrical detonation by using a 500-mm-diam-cylindrical-combustor.

Wakita, Masashi; Tamura, Masayoshi; Terasaka, Akihiro; Sajiki, Kazuya; Totani, Tsuyoshi; Nagata, Harunori

219

Detonation initiation techniques for pulse detonation propulsion  

NASA Astrophysics Data System (ADS)

The paper outlines recent efforts of the research team directed by the author on the development of efficient means for reducing the deflagration-to-detonation transition (DDT) run-up distance and time for liquidfueled air-breathing pulse detonation engine (PDE) applications. The main objective of the studies was to ensure fast DDT in a PDE tube at the lowest possible ignition energy, at the shortest distance, with the lowest pressure loss, and using aviation kerosene TS-1 (Russian analogue of JetA) as fuel and air as oxidizer.

Frolov, S. M.

2009-09-01

220

Experimental Method to Determine the Detonation Characteristics of a Very Non-Ideal High Explosive  

NASA Astrophysics Data System (ADS)

Common experimental configurations used to determine HE detonation velocity-curvature are right circular cylinders detonated in air. The steadily propagating detonation front is curved and its velocity depends upon the diameter of the cylinder. This configuration requires several experiments with different diameters and sufficiently long cylinders to assume a steadily propagating detonation front. This last hypothesis is practically not achieved for non-ideal HE using reasonably long cylinders. To elude this problem, a special explosive device called ``logosphere'', developed by CEA, has been adapted to non ideal HE. It provides a well define spherically diverging detonation wave and allows measurements of the detonation velocity-curvature relationship by means of piezoelectric pins without any perturbation. VISAR and IDL diagnostics record the material velocities at the rear surface of the explosive through transparent windows. The particle velocity values are used to determine the curved detonation states using the detonation velocity-acceleration-curvature model of Louis Brun.

Baudin, G.; Le Gallic, C.; Davoine, F.; Bouinot, P.

2006-07-01

221

Experimental Method to Determine the Detonation Characteristics of Very Non-Ideal High Explosives  

NASA Astrophysics Data System (ADS)

Common experimental configurations used to determine HE detonation velocity-curvature are right circular cylinders detonated in air. The steadily propagating detonation front is curved and its velocity depends upon the diameter of the cylinder. This configuration requires several experiments with different diameters and sufficiently long cylinders to assume a steadily propagating detonation front. This last hypothesis is practically not achieved for non-ideal HE using reasonably long cylinders. To elude this problem, a special explosive device called ``logosphere,'' developed by CEA, has been adapted to non ideal HE. It provides a well define spherically diverging detonation wave and allows measurements of the detonation velocity-curvature relationship by means of piezoelectric pins without any perturbation. VISAR and DLI diagnostics record the material velocities at the rear surface of HE through transparent windows. The particle velocity values are used to determine the curved detonation states using the detonation velocity-acceleration-curvature model of Louis Brun.

Baudin, Gerard

2005-07-01

222

Multiphase Detonations for Pulse Detonation Rocket Engines.  

National Technical Information Service (NTIS)

Recent efforts in PDRE research at AFRL-West have focused on basic studies of the detonation or constant-volume combustion of multiphase mixtures. A collaborative effort is under way for developing models appropriate for PDRE application studies. This eff...

D. G. Talley E. B. Coy J. M. Watts

2002-01-01

223

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

224

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

225

Modelling detonation in ultrafine tatb hemispherical boosters using crest  

NASA Astrophysics Data System (ADS)

Hemispherical ultrafine TATB boosters can initiate detonation in the TATB-based explosive LX-17. For accurate hydrocode predictions of experiments using this combination of explosives, it is important to accurately model the detonation wave emerging from the booster material since this may influence the detonation behaviour in the main charge. Since ultrafine TATB exhibits non-ideal detonation behaviour, its response should be modelled using reactive flow. In this paper, the CREST reactive burn model, which uses entropy-dependent reaction rates to simulate explosive behaviour, is applied to LLNL experimental data obtained from ultrafine TATB hemispherical boosters initiated by slapper detonators at three initial temperatures (ambient, -20°C, and -54°C). The ambient temperature data is used to develop an initial CREST model for ultrafine TATB which is then subsequently applied to the cold data. A comparison of the experimental and modelling results is presented showing that the model gives good agreement to experiment at both ambient and cold temperatures

Whitworth, Nicholas J.

2012-03-01

226

Pulse Detonation Engine Modeled.  

National Technical Information Service (NTIS)

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 proc...

D. E. Paxson

2001-01-01

227

Computer modeling of detonators.  

National Technical Information Service (NTIS)

A mathematical model of detonators which describes the resistance of the exploding bridgewire or exploding foil initiator as a function of energy deposition will be described. This model includes many parameters that can be adjusted to obtain a close fit ...

C. M. Furnberg

1994-01-01

228

Simulating Sympathetic Detonation Effects.  

National Technical Information Service (NTIS)

In an effort, to understand the mechanism causing sympathetic detonation, a concurrent calculational/experimental research program was initiated. The primary objective of this work was to predict the propensity of a given energetic formulation to sympathe...

J. G. Glenn

1993-01-01

229

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

230

Direct observation detonator operation  

NASA Astrophysics Data System (ADS)

The analysis of detonator-timing performance has involved the use of rotating-mirror cameras (RMC) used in the streak mode and high-speed film. Fiducial timing marks are applied to the film to provide temporal references. The use of a RMC for detonator analysis requires aligning the camera, performing an exposure test, capturing light from the detonation and then processing the film. This procedure can take up to an hour for two technicians. After the film is possessed another technician compares each light streak on the film with the fiducial timing marks also recorded on the film. Capturing light from a detonator and recording it directly to a digitizer can improve detonator-timing measurement in several ways. The digitized signals can then be directly analyzed with software. The direct recording method reduces the need for expensive rotating mirror cameras, film processing and subjective optical measurement comparison. Furthermore, an extensive support facility requiring several specialized technicians is reduced to a single technician in a modest laboratory. This technician is then capable of performing several tests an hour. Tests were preformed to measure light intensity at detonation. An optical method of capturing the light was designed using a remote microscope coupled to optical fiber to bring the light to an optical/electrical converter and a digitizer then records the signal. This system is presently used in parallel with a RMC. The results are compared for accuracy.

Hall, Charles R.

2001-11-01

231

Effect of chemical reactivity on the detonation initiation in shock accelerated flow in a confined space  

NASA Astrophysics Data System (ADS)

The interactions of a spherical flame with an incident shock wave and its reflected shock wave in a confined space were investigated using the three-dimensional reactive Navier-Stokes equations, with emphasis placed on the effect of chemical reactivity of mixture on the flame distortion and detonation initiation after the passage of the reflected shock wave. It is shown that the spatio-temporal characteristics of detonation initiation depend highly on the chemical reactivity of the mixture. When the chemical reactivity enhances, the flame can be severely distorted to form a reactive shock bifurcation structure with detonations initiating at different three-dimensional spatial locations. Moreover, the detonation initiation would occur earlier in a mixture of more enhanced reactivity. The results reveal that the detonations arise from hot spots in the unburned region which are initiated by the shock-detonation-transition mechanism.

Zhu, Yue-Jin; Dong, Gang; Liu, Yi-Xin; Fan, Bao-Chun; Jiang, Hua

2013-02-01

232

Subnanosecond measurements of detonation fronts in solid high explosives  

SciTech Connect

Detonation fronts in solid high explosives have been examined through measurements of particle velocity histories resulting from the interaction of a detonation wave with a thin metal foil backed by a water window. Using a high time resolution velocity-interferometer system, experiments were conducted on three explosives: a TATB (1,3,5-triamino-trinitrobenzene)-based explosive called PBX-9502, TNT (2,4,6-Trinitrotoluene), and CP (2-)5-cyanotetrazolato) pentaamminecobalt )III) perchlorate). In all cases, detonation-front rise times were found to be less than the 300 ps resolution of the interferometer system. The thermodynamic state in the front of the detonation wave was estimated to be near the unreacted state determined from an extrapolation of low-pressure unreacted Hugoniot data for both TNT and PBX-9502 explosives. Computer calculations based on an ignition and growth model of a Zeldovich--von Neumann--Doering (ZND) detonation wave show good agreement with the measurements. By using the unreacted Hugoniot and a JWL equation of state for the reaction products, we estimated the initial reaction rate in the high explosive after the detonation wave front interacted with the foil to be 40 ..mu..s/sup -1/ for CP, 60 ..mu..s/sup -1/ for TNT, and 80 ..mu..s/sup -1/ for PBX-9502. The shape of the profiles indicates the reaction rate decreases as reaction proceeds.

Sheffield, S.A.; Bloomquist, D.D.; Tarver, C.M.

1984-04-15

233

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

234

Continuous detonation in the regime of self-oscillatory ejection of the oxidizer. 2. Air as an oxidizer  

Microsoft Academic Search

Results of an experimental study of continuous detonation of a hydrogen-air mixture in a flow-type annular combustor 306 mm\\u000a in diameter in the regime of air self-ejection are reported. The regime of pulsed detonation is also obtained. Stable regimes\\u000a of continuous detonation with one and two transverse detonation waves having velocities D = 1.48?1.16 km\\/sec are observed in experiments. The

F. A. Bykovskii; S. A. Zhdan; E. F. Vedernikov

2011-01-01

235

Detonation failure characterization of non-ideal explosives  

Microsoft Academic Search

Current methods of characterizing non-ideal explosives require large-scale testing to obtain steady detonation wave propagation for analysis due to the relatively thick reaction zones. A small scale experiment would be very useful in quickly characterizing many materials. Use of a microwave interferometer applied to small-scale confined transient experiments was implemented yielding time resolved characterization of a failing detonation that is

Robert S Janesheski

2011-01-01

236

Rapid detonation initiation by sparks in a short duct: a numerical study  

NASA Astrophysics Data System (ADS)

Rapid onset of detonation can efficiently increase the working frequency of a pulse detonation engine (PDE). In the present study, computations of detonation initiation in a duct are conducted to investigate the mechanisms of detonation initiation. The governing equations are the Euler equations and the chemical kinetic model consists of 19 elementary reactions and nine species. Different techniques of initiation have been studied for the purpose of accelerating detonation onset with a relatively weak ignition energy. It is found that detonation ignition induced by means of multiple sparks is applicable to auto-ignition for a PDE. The interaction among shock waves, flame fronts and the strip of pre-compressed fresh (unburned) mixture plays an important role in rapid onset of detonation.

Hu, Z. M.; Dou, H. S.; Khoo, B. C.

2010-06-01

237

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

238

Optimization study of spray detonation initiation by electric discharges  

NASA Astrophysics Data System (ADS)

Development of air-breathing pulse detonation engines is faced with a challenging problem of detonation initiation in fuel sprays at distances feasible for propulsion applications. Extensive experimental study on initiation of a confined n-hexane spray detonation in air by electric discharges is reported. It is found that for direct initiation of spray detonation with minimal energy requirements (1) it is worth to use one discharger located near the closed end of a detonation tube and at least one additional discharger downstream from it to be triggered in-phase with primary shock wave arrival; (2) the discharge area should be properly insulated to avoid electric loss to metal tube walls; (3) discharge duration should be minimized to at least 50 ?s; (4) discharge channel should preferably occupy a large portion of a tube cross-section; (5) test tube should be preferably of a diameter close to the limiting tube diameter; (6) gradual transition between the volume with electric discharger and the tube should be used; and (7) a powerful electric discharger utilized for generating a primary shock wave can be replaced by a primary shock wave generator comprising a relatively low-energy electric discharger, Shchelkin spiral, and tube coil. With all these principles implemented, the rated electric energy of about 100 J was required to initiate n-hexane spray air detonation in a 28-mm tube at a distance of about 1 m from the atomizer.

Frolov, S. M.; Basevich, V. Ya.; Aksenov, V. S.; Polikhov, S. A.

2005-11-01

239

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

240

Evaluation of TiN and CrN surface coatings with laser-supported thermography  

NASA Astrophysics Data System (ADS)

With the PVD (physical-vapor-deposition) technology various metallic and ceramic coatings, for example coatings like TiN and CrN, can be used on different materials as wear- resistant coatings. To verify the quality of the coating especially on components with a complex shape the nondestructive testing of the coating properties is very important. Established nondestructive testing techniques like ultrasonic and eddy current techniques often fail for thin coatings because of the large wavelength. In this article the possibilities and limits of the laser supported thermography for the characterization of such coatings are presented and discussed. Beside the thermal wave technique using a periodic laser heating and an infrared detection from the front side of the component the transient behavior of the temperature in the case of a step like heating is analyzed. By a systematic variation of the measurement parameters and comparison with calculations about the heat flow in coating systems the thermal properties near the surface of the component are analyzed. The results of the laser supported thermography are compared with the results of a metallography of the coatings.

Radtke, U.; Crostack, Horst-Artur

1996-08-01

241

DETONATION PRESSURE MEASUREMENTS ON PETN  

Microsoft Academic Search

PETN is widely recognized as an example of nearly ideal detonation performance. The chemical composition is such that little or no carbon is produced in the detonation products. The reaction zone width is less than currently detectable. (<1 ns) Observations on PETN have thus become a baseline for EOS model predictions. It has therefore become important to characterize the detonation

L G Green; E L Lee

2006-01-01

242

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

243

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

244

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

245

Modeling LX17 Detonation Growth and Decay Using the Ignition and Growth Reactive Flow Model  

Microsoft Academic Search

The Ignition and Growth reactive flow model parameters for detonation waves in the TATB-based insensitive high explosive LX-17 are applied to two recent experiments. One experiment measures the slow increases in detonation velocity and pressure over several centimeters in confined charges as the steady state Chapman-Jouguet (C-J) values are approached. A second experiment measures the rate of detonation failure in

Craig Tarver; Steven Chidester

2009-01-01

246

RESPONSE OF ALUMINUM SPHERES IN SITU TO DETONATION  

SciTech Connect

Time sequence x-ray imaging was utilized to determine the response of aluminum spheres embedded in a detonating high-explosive cylinder. The size of these spheres ranged from 3/8-inch to 1/32-inch in diameter. These experiments directly observed the response of the spheres as a function of time after interaction with the detonation wave. As the spheres are entrained in the post-detonation flow field, they are accelerating and their velocity profile is complicated, but can be determined from the radiography. Using the aluminum spheres as tracers, radial velocities of order 1.6 mm/us and horizontal velocities of order 0.08 mm/us were measured at early times post detonation. In terms of response, these data show that the largest sphere deforms and fractures post detonation. The intermediate size spheres suffer negligible deformation, but appear to ablate post detonation. Post detonation, the smallest spheres either react, mechanically disintegrate, atomize as a liquid or some combination of these.

Molitoris, J D; Garza, R G; Tringe, J W; Batteux, J D; Wong, B M; Villafana, R J; Cracchiola, B A; Forbes, J W

2010-03-26

247

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

248

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.

249

Computer modeling of detonators  

Microsoft Academic Search

A mathematical model of detonators which describes the resistance of the exploding bridgewire or exploding foil initiator as a function of energy deposition will be described. This model includes many parameters that can be adjusted to obtain a close fit to experimental data. This has been demonstrated using recent experimental data taken within Sandia National Laboratories

C. M. Furnberg

1994-01-01

250

Analogie Explosionswelle-Kopfwelle Nahe Gekruemmten Waenden (Analogy between Explosive Wave and Front Wave Near Curved Walls).  

National Technical Information Service (NTIS)

Three dimensional steady flow field propagation around a curved wall is investigated by means of analogy with a two dimensional non steady state detonation wave. Analytical detonation wave equations are transformed taking in account the shock front surfac...

K. W. Naumann

1987-01-01

251

Environmentally Benign Stab Detonators  

SciTech Connect

Many energetic systems can be activated via mechanical means. Percussion primers in small caliber ammunition and stab detonators used in medium caliber ammunition are just two examples. Current medium caliber (20-60mm) munitions are detonated through the use of impact sensitive stab detonators. Stab detonators are very sensitive and must be small, as to meet weight and size limitations. A mix of energetic powders, sensitive to mechanical stimulus, is typically used to ignite such devices. Stab detonators are mechanically activated by forcing a firing pin through the closure disc of the device and into the stab initiating mix. Rapid heating caused by mechanically driven compression and friction of the mixture results in its ignition. The rapid decomposition of these materials generates a pressure/temperature pulse that is sufficient to initiate a transfer charge, which has enough output energy to detonate the main charge. This general type of ignition mix is used in a large variety of primers, igniters, and detonators.[1] Common primer mixes, such as NOL-130, are made up of lead styphnate (basic) 40%, lead azide (dextrinated) 20%, barium nitrate 20%, antimony sulfide 15%, and tetrazene 5%.[1] These materials pose acute and chronic toxicity hazards during mixing of the composition and later in the item life cycle after the item has been field functioned. There is an established need to replace these mixes on toxicity, health, and environmental hazard grounds. This effort attempts to demonstrate that environmentally acceptable energetic solgel coated flash metal multilayer nanocomposites can be used to replace current impact initiated devices (IIDs), which have hazardous and toxic components. Successful completion of this project will result in IIDs that include innocuous compounds, have sufficient output energy for initiation, meet current military specifications, are small, cost competitive, and perform as well as or better than current devices. We expect flash metal multilayer and sol-gel to be generic technologies applicable to a wide range of devices, especially in small caliber ammunition and sub-munitions. We will replace the NOL-130 mixture with a nanocomposite that consists of a mechanically robust energetic multilayer foil that has been coated with a sol-gel energetic material. The exothermic reactions are activated in this nanocomposite are the transformation of the multilayer material to its respective intermetallic alloy and the thermite reaction, which is characterized by very high temperatures, a small pressure pulse, and hot particle ejection. The proposed materials and their reaction products consist of, but are not limited to aluminum, nickel, iron, aluminum oxide, titanium, iron oxide and boron. These materials have much more desirable environmental and health characteristics than the NOL-130 composition.

Gash, A

2005-12-21

252

Multi-Scaled Cellular Detonation  

NASA Astrophysics Data System (ADS)

Experimental evidence of the three-dimensional features of detonation fronts can be traced back to the work of Campbell and Woodhead [9] and Bone and Fraser [6] for marginal detonations propagating in tubes. Manson [64] and Fay [36] established an acoustic theory that provided a reasonable explanation for these observations, without knowledge of the intrinsic nature of the detonation structure. In 1959, Denisov and Troshin [18] discovered the real detonation front structure (Fig. 5.1). Their results showed that the detonation reaction zone was locally transient, thus leading to three-dimensional periodic instabilities. Since then, numerous studies of modern detonation physics have been dedicated to the so-called cellular structure of the detonation front.

Desbordes, Daniel; Presles, Henri-Noël

253

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

254

Non-ideal detonation behaviour of PBX 9502  

NASA Astrophysics Data System (ADS)

Numerical experiments are performed investigating the non-ideal detonation behaviour of PBX 9502 in two setups. In the first setup we consider a three-dimensional rate stick experiment. A booster charge initiates a reaction front leading to a curved detonation wave. The numerical results are compared to theory and experimental evidence. The effects of weak and strong confinement are discussed. The second setup considers the so called ``hockey puck experiment.'' Experimental results show the appearance of a dead zone due to the effect of the geometry. This is captured by the numerical results, which also reveal that the initially spherical detonation is diffracted leading to local detonation failure. The numerical simulations are performed by solving a mathematical model for a three-phase medium based on the Euler equations. The numerical results are obtained using high-resolution shock-capturing methods combined with adaptive mesh refinement.

Schoch, Stefan; Nikiforakis, Nikos

2009-06-01

255

Experimental Study of Key Issues on Pulse Detonation Engine Development  

NASA Astrophysics Data System (ADS)

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 the two jets. A good agreement is obtained between the calculated and measured mixing ratios, indicating the occurrence of nearly instant mixing. Before the detonation velocity has reached the CJ value, it was found that the wave propagation velocity at the PDE exit increases with the increase in diameter, length and blockage ratio of the Shchelkin wire, and initial pressure. The PDE performance acquired was a specific impulse of about 2000 s, which was measured from the pressure history at the head end of the PDE.

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

256

The role of instability in gaseous detonation  

NASA Astrophysics Data System (ADS)

In detonation, the coupling between fluid dynamics and chemical energy release is critical. The reaction rate behind the shock front is extremely sensitive to temperature perturbations and, as a result, detonation waves in gases are always unstable. A broad spectrum of behavior has been reported for which no comprehensive theory has been developed. The problem is extremely challenging due to the nonlinearity of the chemistry-fluid mechanics coupling and extraordinary range of length and time scales exhibited in these flows. Past work has shown that the strength of the leading shock front oscillates and secondary shock waves propagate transversely to the main front. A key unresolved issue has emerged from the past 50 years of research on this problem: What is the precise nature of the flow within the reaction zone and how do the instabilities of the shock front influence the combustion mechanism?This issue has been examined through dynamic experimentation in two facilities. Key diagnostic tools include unique visualizations of superimposed shock and reaction fronts, as well as short but informative high-speed movies. We study a range of fuel-oxidizer systems, including hydrocarbons, and broadly categorize these mixtures by considering the hydrodynamic stability of the reaction zone. From these observations and calculations, we show that transverse shock waves do not essentially alter the classic detonation structure of Zeldovich-von Neumann-Doring (ZND) in weakly unstable detonations, there is one length scale in the instability, and the combustion mechanism is simply shock-induced chemical-thermal explosion behind a piecewise-smooth leading shock front. In contrast, we observe that highly unstable detonations have substantially different behavior involving large excursions in the lead shock strength, a rough leading shock front, and localized explosions within the reaction zone. The critical decay rate model of Eckett et al. (JFM 2000) is combined with experimental observations to show that one essential difference in highly unstable waves is that the shock and reaction front may decouple locally. It is not clear how the ZND model can be effectively applied in highly unstable waves. There is a spectrum of length scales and it may be possible that a type of "turbulent" combustion occurs. We consider how the coupling between chemistry and fluid dynamics can produce a large range of length scales and how possible combustion regimes within the front may be bounded.

Austin, Joanna Maria

257

Shock pressure determination in detonator wires  

SciTech Connect

High-resolution microstreak photographs were used to record shock waves from water-immersed, exploding detonator wires. Shock velocities were read directly from the photographs, and pressures were computer from known Hugoniot data. Wires were gold or aluminium, 35 /mu/m in diameter by 1 mm long. The field of the streak camera covered a spatial width of about 1 mm and a time interval of 200 to 500 ns with resolutions of about 5 /mu/m and 1 ns, respectively. Initial hand reduction of data, and the quadratic form of the Hugoniot, resulted in substantial data spread. Computer image analysis has reduced the spread, although questions of interpretation and accuracy remain. Observation included waves generated by melting of the wire and by rebound of the melt wave. Shockwave pressures of over 15 kbar were generated, predominantly by the rebound wave from the burst, which overtakes the initial burst wave. 4 refs., 3 figs.

Frank, A.M.; Gathers, G.R.

1989-07-21

258

Some perspectives on pulse detonation propulsion systems  

NASA Astrophysics Data System (ADS)

Pulse detonation engines and rockets (PDE/Rs) can potentially revolutionize air breathing and rocket propulsion [1-6]. While the PDE concept is over five decades old, it has recently enjoyed renewed interest, due mostly to theoretical and computational studies indicating high cycle efficiencies. When modeled by a constant volume, Humphrey cycle, the detonation engine is found to be superior to that of existing constant pressure, Brayton cycles, with claims of as much as 10-40% improvement in specific impulse [4,7-9]. The constant volume process is derived from the Zeldovich-von Neumann-Döring (ZND) model of the detonation wave as a high strength shock wave, followed by a region of chemical reaction and a subsequent isentropic rarefaction. Amongst other advantages of the PDE is simplicity, where the PDE is easy to manufacture and requires few moving parts, with the possibility of eliminating high-pressure pumps in rocket applications, or reducing turbomachinery stages in air-breathing propulsion systems.

Lu, F. K.; Wilson, D. R.

259

Analogy between explosive wave and front wave near curved walls  

NASA Astrophysics Data System (ADS)

Three dimensional steady flow field propagation around a curved wall is investigated by means of analogy with a two dimensional non steady state detonation wave. Analytical detonation wave equations are transformed taking in account the shock front surface changes with the detonation wave radius. A family of spiraloid concave contour lines is obtained for which Sakurai distribution functions are applied. For the other contour configurations, a short time energy source is proposed.

Naumann, K. W.

1987-04-01

260

Analytical Estimation of Performance Parameters of an Ideal Pulse Detonation Engine  

NASA Astrophysics Data System (ADS)

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 rarefaction wave started to propagate from the open end toward the closed end. We analytically obtained a functional form of the thrust-density history, showing a plateau followed by decay. Using the obtained history of the thrust density, we formulated some PDE performance parameters such as impulse density per cycle.

Endo, Takuma; Fujiwara, Toshi

261

Using Schlieren Visualization to Track Detonator Performance  

Microsoft Academic Search

Several experiments that are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation to full detonation to transition to booster and booster detonation will be presented. High Speed Laser Schlieren Movies have been used to study several explosive initiation events, such as exploding bridgewires (EBW), Exploding Foil Initiators

Steven Clarke; Keith Thomas; Michael Martinez; Adrian Akinci; Michael Murphy; Ronald Adrian

2007-01-01

262

USING SCHLIEREN VISUALIZATION TO TRACK DETONATOR PERFORMANCE  

Microsoft Academic Search

Several experiments will be presented that are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation, to full detonation, to transition, to booster and booster detonation. High-speed multiframe schlieren imagery has been used to study several explosive initiation events, such as exploding bridgewires (EBWs), exploding foil initiators (EFIs

S. A. Clarke; C. A. Bolme; M. J. Murphy; C. D. Landon; T. A. Mason; R. J. Adrian; A. A. Akinci; M. E. Martinez; K. A. Thomas

2007-01-01

263

Using Schlieren Visualization to Track Detonator Performance  

Microsoft Academic Search

Several experiments will be presented that are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation, to full detonation, to transition, to booster and booster detonation. High-speed multiframe schlieren imagery has been used to study several explosive initiation events, such as exploding bridgewires (EBWs), exploding foil initiators (EFIs

S. A. Clarke; C. A. Bolme; M. J. Murphy; C. D. Landon; T. A. Mason; R. J. Adrian; A. A. Akinci; M. E. Martinez; K. A. Thomas

2007-01-01

264

Delayed detonations in full-star models of Type Ia supernova explosions  

Microsoft Academic Search

Aims: We present the first full-star three-dimensional explosion simulations\\u000aof thermonuclear supernovae including parameterized deflagration-to-detonation\\u000atransitions that occur once the flame enters the distributed burning regime.\\u000aMethods: Treating the propagation of both the deflagration and the detonation\\u000awaves in a common front-tracking approach, the detonation is prevented from\\u000acrossing ash regions. Results: Our criterion triggers the detonation wave at\\u000athe

F. K. Roepke; J. C. Niemeyer

2007-01-01

265

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

266

Precursors in detonations in porous explosives  

SciTech Connect

Photographs of detonation waves in low-density HMX and PETN, made with an image-intensifier camera, show a brilliant band of light in front of the pressure jump. The radiation temperature is estimated to be 12,000 to 14,000/sup 0/K. The spectrum of this light is continuous. A quartz gauge shows a gradual buildup of pressure from the material producing the light. The material has little effect on the propagation of detonation. Further observations, using pellets of plastic-bonded HMX and single crystals of PETN, show that the material thrown off the free surface is transparent, with a leading edge moving at approximately 20 mm/..mu..s. Collision of this material with polymethyl methacrylate (PMMA) produces a brilliant light with a spectrum that is initially a narrow H/sub ..cap alpha../ line. Quartz gauges measure the rate of pessure buildup of this material.

Spaulding, R.L. Jr.

1981-01-01

267

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

268

Safeguarding against sympathetic detonations  

SciTech Connect

This article describes research to develop explosives with superior blasting power that can survive accidental initiation. The importance of being able to prevent detonations can be gleaned from the Air Force's inventory of hundreds of thousands of 500-pound general-purpose bombs, which are its main weapons. A 500-pound bomb contains approximately 200 pounds of high explosive; the remainder of the bomb's weight is its steel casing. The explosive used is a combination of TNT and aluminum. The chemists at the US Air Force's High Explosives Research and Development (HERD) facility are working on modifying the formulation so that it will be insensitive to the kind of jolt emanating from the detonation of a nearby bomb. At the same time, the bomb must maintain high performance.

Glenn, J.G. (Wright Lab. Armament Directorate, Eglin Air Force Base, FL (United States). Energetic Materials Branch); Gunger, M. (Orlando Technology Inc., Shalimar, FL (United States))

1994-02-01

269

A Non-Ideal Detonation Model for Evaluating the Performance of Explosives in Rock Blasting  

NASA Astrophysics Data System (ADS)

A new model to predict the non-ideal detonation behaviour of commercial explosives in rock blasting is presented. The model combines the slightly divergent flow theory, polytropic equation of state, simple pressure-dependent rate law and statistical expressions to model the effect of confinement on detonation. The model has been designated as DeNE, an acronym for the Detonics of Non-ideal Explosives. It is aimed at predicting the detonation state and subsequent rarefaction (Taylor) wave to provide the pressure history for different explosive, rock type and blasthole diameter combinations. It enables the prediction and comparison of the performance of commercial explosives in different blasting environments. The unconfined detonation velocity data has been obtained from the testing of six commercial explosives to calibrate DeNE. A detailed sensitivity analysis has been conducted to evaluate the model. The model has been validated using the results of hydrocodes as well as measured and published in-hole detonation velocity data.

Esen, S.

2008-06-01

270

Initial hydrogen detonation data from the High-Temperature Combustion Facility  

SciTech Connect

The Brookhaven National Laboratory High-Temperature Combustion Facility (HTCF) is described and data from initial hydrogen detonation experiments are presented. Initial phase of the inherent detonability experimental program is described. Test gases thus far tested are hydrogen-air mixtures at one atmosphere initial pressure and temperatures 300K-650K. Detonation pressure, wave speed, and detonation cell size were measured. Data were consistent with earlier SSDA (small-scale development apparatus) test results. HTCF results confirm the conclusion from the SSDA program that the gas temperature decreases the cell size and, therefore, increases the sensitivity of mixtures to detonation. Data from the larger HTCF test vessel, however, also demonstrates that the effect of increased scale is to extend the range of detonable mixtures to lower concentration.

Ginsberg, T.; Ciccarelli, G.; Boccio, J. [and others

1994-12-31

271

Experimental Study on DDT Characteristics in Spiral Configuration Pulse Detonation Engines  

NASA Astrophysics Data System (ADS)

This work investigated features of the deflagration to detonation transition in a curved tube. A number of experiments were performed to acquire the transition rule of DDT, which would provide the design data and theoretical basis for the curved detonation chamber. The content of research is as follows: (1) Flow resistance experiments of nine detonation chambers have been explored. The results show that the spiral configuration can reduce the axial length of DC, and the total pressure recovery coefficient increases with the spiral pitch. (2) Single-cycle detonation experiments have been conducted using the 9 tubes in the resistance experiments. Liquid-gasoline/air is used as the detonative mixture in all the experiments. The detonation experimental results indicate that there is no detonation wave formed in the straight tube, but in all the selected spiral tubes fully-developed detonation waves have been obtained; compared to the straight tube case, the DDT time decrease with the decreasing of the radius of curvature (RC) by 6.2%˜19.8% in the spiral detonation tubes.

Wang, Wei; Qiu, Hua; Fan, Wei; Xiong, Cha

2013-09-01

272

Transmission of Thermonuclear Detonations through Layers of Burned Material in Carbon-Oxygen White Dwarfs  

NASA Astrophysics Data System (ADS)

In three-dimensional delayed-detonation models of type Ia supernovae, detonations propagate through funnels of degenerate carbon-oxygen matter that are left unburned by turbulent deflagrations in central parts of a white dwarf. Some of these funnels can be disconnected from the rest of the unburned material, thus creating unburned pockets that cannot be directly reached by a detonation wave. These pockets may or may not ignite when strong shocks generated by detonations reach them through layers of burned material. In this work, we study the detonation transmission phenomena in exploding white dwarfs using one-dimensional time-dependent numerical simulations based on reactive Euler equations. The thermonuclear burning of carbon-oxygen mixture is modeled by a 13-nuclei alpha network. We use a steady-state solution for the reaction-zone structure of a one-dimensional detonation wave as an initial condition. Time-dependent computations performed for a fully resolved carbon reaction scale show that a detonation shock passing through a layer of burned material can initiate a new detonation or decay. The critical thickness of burned material that allows the detonation reignition is a function of density. This work was supported in part by the NASA ATP program (NRA-02-OSS-01-ATP) and by the Naval Research Laboratory (NRL) through the Office of Naval Research.

Gamezo, V. N.; Oran, E. S.

2006-06-01

273

Recent work on gaseous detonations  

Microsoft Academic Search

.   The paper reviews recent progress in the field of gaseous detonations, with sections on shock diffraction and reflection,\\u000a the transition to detonation, hybrid, spherically-imploding, and galloping and stuttering fronts, their structure, their transmission\\u000a and quenching by additives, the critical energy for initiation and detonation of more unusual fuels. The final section points\\u000a out areas where our understanding is still

M. A. Nettleton

2002-01-01

274

Recent work on gaseous detonations  

NASA Astrophysics Data System (ADS)

The paper reviews recent progress in the field of gaseous detonations, with sections on shock diffraction and reflection, the transition to detonation, hybrid, spherically-imploding, and galloping and stuttering fronts, their structure, their transmission and quenching by additives, the critical energy for initiation and detonation of more unusual fuels. The final section points out areas where our understanding is still far from being complete and contains some suggestions of ways in which progress might be made.

Nettleton, M. A.

275

Laser-supported solid-state absorption fronts in silica  

NASA Astrophysics Data System (ADS)

We develop a model based on simulation and extensive experimentation that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm2 ) laser exposure. Both experiments and simulations show 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. We show that these absorption fronts naturally result from the combination of high-temperature-activated deep subband-gap optical absorptivity, free-electron transport, and thermal diffusion in defect-free silica for temperatures up to 15000K and pressures <10GPa . 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.; Demange, P.

2010-11-01

276

Electrostatic discharge effects on EBW detonators.  

National Technical Information Service (NTIS)

With appropriate circuit resistance and inductance and sufficient stored energy, discharging a charged human body or component through an exploding bridgewire (EBW) detonator may cause the detonator to function or may damage the detonator. We have studied...

R. S. Lee R. E. Lee

1991-01-01

277

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

278

Detonation failure characterization of non-ideal explosives  

NASA Astrophysics Data System (ADS)

Non-ideal explosives are currently poorly characterized, hence limiting the modeling of them. Current characterization requires large-scale testing to obtain steady detonation wave characterization for analysis due to the relatively thick reaction zones. Use of a microwave interferometer applied to small-scale confined transient experiments is being implemented to allow for time resolved characterization of a failing detonation. The microwave interferometer measures the position of a failing detonation wave in a tube that is initiated with a booster charge. Experiments have been performed with ammonium nitrate and various fuel compositions (diesel fuel and mineral oil). It was observed that the failure dynamics are influenced by factors such as chemical composition and confiner thickness. Future work is planned to calibrate models to these small-scale experiments and eventually validate the models with available large scale experiments. This experiment is shown to be repeatable, shows dependence on reactive properties, and can be performed with little required material.

Janesheski, Robert S.; Groven, Lori J.; Son, Steven

2012-03-01

279

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

280

Predictions of pressure and composition limits for confined hydrogen-oxygen detonations. Final report  

SciTech Connect

Pressure and composition limits, and velocity deficits have been calculated for confined hydrogen-oxygen detonations, and the effect of initial pressure, mixture composition, and tube diameter on detonability limits has been investigated. A quasi-one-dimensional Zeldovich-von-Neumann-Doring model is used to represent the reaction zone, and the effect of the viscous boundary layer along the wall is accounted for using a negative displacement thickness. The model predicts all the experimentally observed features of detonation waves; (a) all confined detonation waves travel at a velocity somewhat lower than the C-J velocity, and the velocity deficit is dependent on pressure, gas composition, and tube diameter; (b) detonability limits exist and again depend on pressure, composition and tube diameter. Effect of the chemical reaction scheme and multidimensional effects are also discussed.

Semerjian, H.G.; Dove, J.E.

1981-01-01

281

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

282

Characterizing detonator output using dynamic witness plates  

SciTech Connect

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 John [Los Alamos National Laboratory; Adrian, Ronald J [Los Alamos National Laboratory

2009-01-01

283

Numerical Simulations of Detonation Instabilities and Magnetic Field Interactions  

NASA Astrophysics Data System (ADS)

Numerical simulations of magneto-hydrodynamic (MHD) effects on high frequency and low frequency one-dimensional detonation wave instabilities are performed, with applications to flow control and MHD thrust augmentation in Pulse Detonation Engines and their design variations.ootnotetextZeineh, et al., J. Propusion & Power, to appear The dynamics of the hydrogen-air detonation are explored via high order shock capturing schemes and complex reaction kinetics. The flame is initially strongly coupled to the shock and the wave is over-driven. As the degree of overdrive decays and the detonation approaches the CJ limit, high frequency instabilities begin to appear. Eventually the average induction length continues to increase and a second mode can be seen which directly couples the flame speed with the shock, resulting in fluctuations with lower frequency but much higher amplitude. A simple model for flame-shock coupling replicates the quantitative features of these instabilities quite well. Effects of an externally applied magnetic field on these detonation instabilities are explored. In addition, the complex chemical kinetics calculations are ported onto a GPU, and computational performance may be compared with standard CPU-based computations.

Cole, Lord; Le, Hai; Karagozian, Ann

2011-11-01

284

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 mixed with metal particles was experimentally investigated. Aluminum powder with a mean particle size of 6 ?m was used, and the mass concentration of aluminum on the explosive charge ranged from 0 to 30% wt. The values of the detonation velocity, the pressure attenuation - P(x) - of the shock 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 pressuretimes 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 allows a quasicontinuous evaluation of the detonation wave run propagation and the assessment of spatial resolved measurements of the shock wave induced in the PMMA barrier. Results of that characterization process are presented and discussed for aluminized and non-aluminized emulsion explosives. The experimental results have shown that the detonation velocity decreases monotonically with the increase of aluminum content. Nevertheless the peak of detonation pressure profiles presents a non-monotonic behavior increasing its value up to an Al content of 20% wt, after which it starts to decrease.

Mendes, Ricardo; Ribeiro, José B.; Plaksin, I.; Campos, Jose

2012-03-01

285

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

286

Detonation Chemistry: Diffusion Control in Non-Ideal Explosives.  

National Technical Information Service (NTIS)

The performance of an explosive is a function of both the peak energy released near the detonation front, and the remainder of the energy that is released during the Taylor wave. The relative partitioning of energy between the front and the expansion, and...

R. R. McGuire D. L. Ornellas I. Akst

1978-01-01

287

Structure of Detonations in Non-Ideal Stratified Explosives  

Microsoft Academic Search

Stratified explosives are functionally-graded formulations in which the chemical and physical composition changes from point to neighboring point, but gradually. Introducing a gradient in the composition allows the formulator and warhead designer additional degrees of freedom beyond the scope of current uniform, traditional explosives. For example, the shape of the detonation wave can be controlled, directional effects can be directly

Alexandra Landsberg; Raafat Guirguis

2001-01-01

288

Impulse generation by detonation tubes  

Microsoft Academic Search

Impulse generation with gaseous detonation requires conversion of chemical energy into mechanical energy. This conversion process is well understood in rocket engines where the high pressure combustion products expand through a nozzle generating high velocity exhaust gases. The propulsion community is now focusing on advanced concepts that utilize non-traditional forms of combustion like detonation. Such a device is called a

Marcia Ann Cooper

2004-01-01

289

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

290

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

291

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

292

Steady Non-Ideal Detonation  

Microsoft Academic Search

Highly non-ideal explosives, such as commercial ammonium nitrate based explosives used in mining and blasting, have critical charge diameters of several centimetres and relatively low detonation speeds. Shock polar match analyses between these explosives and confining inert materials give two main types of interactions. For the first type (denoted here by case I), the detonation drives an oblique shock into

G. J. Sharpe; M. Y. Luheshi; M. Braithwaite; S. A. E. G. Falle

2009-01-01

293

STEADY NON-IDEAL DETONATION  

Microsoft Academic Search

Highly non-ideal explosives, such as commercial ammonium nitrate based explosives used in mining and blasting, have critical charge diameters of several centimetres and relatively low detonation speeds. Shock polar match analyses between these explosives and confining inert materials give two main types of interactions. For the first type (denoted here by case I), the detonation drives an oblique shock into

G. J. Sharpe; M. Y. Luheshi; M. Braithwaite; S. A. E. G. Falle

2009-01-01

294

Stability of Detonations in Supernovae  

Microsoft Academic Search

Carbon-oxygen thermonuclear detonations in supernovae are unstable at densities above ~= 2 × 107 g cm-3 with respect to longitudinal perturbations. The instability is caused by the positive feedback between hydrodynamical fluctuations and the energy release in the 12C + 12C reaction. The question remains open whether the detonations are stable or not at densities below 2 × 107 g

A. M. Khokhlov

1993-01-01

295

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. 3 figs.

McWilliams, R.A.; Holle, W.G. von.

1983-08-16

296

Detonation diffraction in gases  

SciTech Connect

We have experimentally investigated detonation diffraction out of a round tube into an unconfined half-space. The focus of our study is examining how the extent of detonation cellular instability influences the quantitative and qualitative features of diffraction. Detailed quantitative and qualitative measurements were obtained through simultaneous schlieren imaging, multiple-exposure chemiluminescence imaging, and planar laser-induced fluorescence imaging of OH molecules. Two types of stoichiometric mixtures, highly diluted H{sub 2}-O{sub 2}-Ar and H{sub 2}-N{sub 2}O, were studied in the sub-critical, critical and super-critical regime. These mixture types represent extreme cases in the classification of cellular instability with highly diluted H{sub 2}-O{sub 2}-Ar mixtures having very regular instability structures and H{sub 2}-N{sub 2}O having very irregular instability structures. The most striking differences between the mixtures occur in the sub-critical and critical regimes, for which the detonation fails to transition into the unconfined half-space. For the H{sub 2}-O{sub 2}-Ar mixture, the velocity on the center line was found to decay significantly slower than for the H{sub 2}-N{sub 2}O mixture. In case of the H{sub 2}-O{sub 2}-Ar mixture, it was evident from simultaneous schlieren-fluorescence images that the reaction front was coupled to the lead shock front up to 2.3 tube diameters from the exit plane. For the H{sub 2}-N{sub 2}O mixture, the reaction front velocity decreased to 60% of the corresponding Chapman-Jouguet value at 1.1 tube diameters from the tube exit plane. A geometric acoustic model showed that the observed differences in failure patterns are not caused by the differences in thermodynamic properties of the two mixtures but is linked to the larger effective activation energy and critical decay time in the H{sub 2}-N{sub 2}O mixture as compared to the H{sub 2}-O{sub 2}-Ar mixture. The re-initiation events appear similar for the two mixtures and are a consequence of local fluctuations at random locations within the region between the lead shock and decoupled reaction zone, resulting in strong transverse detonations sweeping through shocked but largely unreacted gas. (author)

Pintgen, F.; Shepherd, J.E. [California Institute of Technology, Mail stop 105-50, 1200 E California Blvd, Pasadena, CA 91125 (United States)

2009-03-15

297

Maximum Entropy of Effective Reaction Theory of Steady Non-ideal Detonation  

Microsoft Academic Search

According to the theory of Byers Brown, in a steady state detonation the entropy production between the shock and sonic locus is a maximum in a self-sustaining wave. This has shown to hold true for all one-dimensional cases. Applied to 2D steady curved detonation waves in a slab or cylindrical stick of explosive, Byers Brown suggested a novel variational approach

Simon Watt; Martin Braithwaite; William Byers Brown; Samuel Falle; Gary Sharpe

2009-01-01

298

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

299

Development of detonations in degenerate stars  

SciTech Connect

It is now widely believed that thermal instability at the center of a carbon-oxygen white dwarf will produce a deflagration wave. In this paper, numerical analysis of the preoutburst conditions near the center of a C-O white dwarf as well as of the three stages of the thermonuclear explosion of the star (i.e., the stages of spontaneous burning front, shock formation, and postshock burning and shock amplification) is presented. It is demonstrated that when a degenerate C-O star explodes as a supernova, thermal instability may cause the thermonuclear burning front to develop into a detonation (rather than a deflagration) regime. 16 references.

Blinnikov, S.I.; Khoklov, A.M.

1986-04-01

300

Study of the Detonation Phase in the Gravitationally Confined Detonation Model of Type Ia Supernovae  

NASA Astrophysics Data System (ADS)

We study the gravitationally confined detonation (GCD) model of Type Ia supernovae (SNe Ia) through the detonation phase and into homologous expansion. In the GCD model, a detonation is triggered by the surface flow due to single-point, off-center flame ignition in carbon-oxygen white dwarfs (WDs). The simulations are unique in terms of the degree to which nonidealized physics is used to treat the reactive flow, including weak reaction rates and a time-dependent treatment of material in nuclear statistical equilibrium (NSE). Careful attention is paid to accurately calculating the final composition of material which is burned to NSE and frozen out in the rapid expansion following the passage of a detonation wave over the high-density core of the WD; and an efficient method for nucleosynthesis postprocessing is developed which obviates the need for costly network calculations along tracer particle thermodynamic trajectories. Observational diagnostics are presented for the explosion models, including abundance stratifications and integrated yields. We find that for all of the ignition conditions studied here a self-regulating process comprised of neutronization and stellar expansion results in final 56Ni masses of ~1.1 M sun. But, more energetic models result in larger total NSE and stable Fe-peak yields. The total yield of intermediate mass elements is ~0.1 M sun and the explosion energies are all around 1.5 × 1051 erg. The explosion models are briefly compared to the inferred properties of recent SN Ia observations. The potential for surface detonation models to produce lower-luminosity (lower 56Ni mass) SNe is discussed.

Meakin, Casey A.; Seitenzahl, Ivo; Townsley, Dean; Jordan, George C., IV; Truran, James; Lamb, Don

2009-03-01

301

Investigation of the detonation regimes in gaseous mixtures with suspended starch particles  

NASA Astrophysics Data System (ADS)

The existence of a secondary discontinuity at the rear of a detonation front shown in experiments by Peraldi and Veyssiere (1986) in stoichiometric hydrogen-oxygen mixtures with suspended 20- ? m starch particles has not been explained satisfactorily. Recently Veyssiere et al. (1997) analyzed these results using a one-dimensional (1-D) numerical model, and concluded that the heat release rate provided by the burning of starch particles in gaseous detonation products is too weak to support a double-front detonation (DFD), in contrast to the case of hybrid mixtures of hydrogen-air with suspended aluminium particles in which a double-front detonation structure was observed by Veyssiere (1986). A two-dimensional (2-D) numerical model was used in the present work to investigate abovementioned experimental results for hybrid mixtures with starch particles. The formation and propagation of the detonation has been examined in the geometry similar to the experimental tube of Peraldi and Veyssiere (1986), which has an area change after 2 m of propagation from the ignition point from a 69 mm dia. section to a 53 mm × 53 mm square cross section corresponding to a 33% area contraction. It is shown that the detonation propagation regime in these experiments has a different nature from the double-front detonation observed in hybrid mixtures with aluminium particles. The detonation propagates as a pseudo-gas detonation (PGD) because starch particles release their heat downstream of the CJ plane giving rise to a non-stationary compression wave. The discontinuity wave at the rear of the detonation front is due to the interaction of the leading detonation front with the tube contraction, and is detected at the farthest pressure gauge location because the tube length is insufficient for the perturbation generated by the tube contraction to decay. Thus, numerical simulations explain experimental observations made by Peraldi and Veyssiere (1986).

Veyssiere, B.; Khasainov, B. A.; Arfi, P.

302

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

303

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

304

Reactive flow modeling of recent embedded gauge and metal acceleration experiments on detonating PBX9404 and LX17  

Microsoft Academic Search

The ignition and growth model of the reactive flow during shock initiation and detonation wave propagation in the heterogeneous solid explosives PBX-9404 and LX-17 is compared to recent embedded particle velocity and stress gauge measurements in detonating PBX-9404 and Fabry-Perot free surface velocity measurements of thin metal plates accelerated by detonating PBX-9404 and LX-17. The overall agreement between the numerical

C. M. Tarver; N. L. Parker; H. G. Palmer; B. Hayes; L. M. Erickson

1983-01-01

305

Detonation properties of the non-ideal explosive PBXW-123  

SciTech Connect

Detonation stability and wave curvature in PBXW-123, an aluminized, non-ideal explosive, have been studied. Reaction failed very slowly in unconfined 75 mm, 100 mm, and 126 mm dia. samples. Peak output pressure was still {approximately}28kb after a run distance of 548 mm in a 126 mm dia. charge. Confinement had a significant effect on reaction stability. Detonation velocity was steady at {approximately}5.5mm/{mu}s in 76 mm dia. samples confined in brass tubes. Reaction wavefront curvature was measured in unconfined and confined samples; detonation wavefront radius of curvature was {approximately}140mm at the centerline in the confined charge. {copyright} {ital 1996 American Institute of Physics.}

Wilson, W.H.; Forbes, J.W.; Gustavson, P.K.; Lemar, E.R.; Sutherland, G.T. [Naval Surface Warfare Center, Indian Head Division, White Oak, Silver Spring, Maryland 20903-5640 (United States)

1996-05-01

306

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

307

Detonation spreading in fine TATBs  

SciTech Connect

A test has been devised that permits rapid evaluation of the detonation-spreading (or corner-turning) properties of detonations in insensitive high explosives. The test utilizes a copper witness plate as the medium to capture performance data. Dent depth and shape in the copper are used as quantitative measures of the detonation output and spreading behavior. The merits of the test are that it is easy to perform with no dynamic instrumentation, and the test requires only a few grams of experimental explosive materials.

Kennedy, J.E.; Lee, K.Y.; Spontarelli, T.; Stine, J.R.

1998-12-31

308

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

309

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

310

Modeling Detonation in Ultrafine TATB Hemispherical Boosters Using CREST  

NASA Astrophysics Data System (ADS)

Hemispherical ultrafine TATB boosters are often used to initiate detonation in the TATB-based explosive LX-17. For accurate hydrocode predictions of experiments using this combination of explosives, it is important to accurately model the detonation wave emerging from the booster material since this may influence the detonation behaviour in the main charge. Since ultrafine TATB exhibits non-ideal detonation behaviour, it's response should be modeled using reactive flow. In this paper, the CREST reactive burn model, which uses entropy- dependent reaction rates to simulate explosive behaviour, is applied to experimental data obtained from ultrafine TATB hemispherical boosters initiated by slapper detonators at three initial temperatures (ambient, -20 degC and -54 degC). The ambient temperature data is used to develop an initial CREST model for ultrafine TATB which is then subsequently applied to the cold data. A comparison of the experimental and modeling results is presented showing that the model gives good agreement to experiment at both ambient and cold temperatures.

Whitworth, Nicholas

2011-06-01

311

Gas-particle interaction in detonation spraying systems  

NASA Astrophysics Data System (ADS)

A model is developed to describe dynamic interaction of particles with the carrier gas during detonation spraying. Equations of mass, energy, and momentum conservation are integrated numerically for the two-phase particle-gas flow with the Hugoniot boundary conditions at the detonation wave front. Velocity and temperature of the sprayed powder and the gas parameters are calculated self-consistently, taking into account effects of friction and cooling of the gas in the vicinity of the gun barrel and effects of particle-gas interaction on the parameters of the gas phase. Calculations are performed for tungsten carbide particles of 30 ?m diam and a 1.8 m long detonation gun using a stoichiometric mixture of oxygen and propane. Distributions of gas and particle parameters along the barrel are calculated for various moments of time. Tungsten carbide particles of 30 ?m reach an exit velocity of 1278 m/s and a temperature of 1950 K. Exit particle velocity is a nonmonotonic function of the loading distance, L, with a distinct maximum at L = 75 cm. The proposed model can be applied to a broad range of problems related to detonation coating technology and allows evaluation of the effectiveness of various designs and optimization of operational parameters of detonation spraying systems.

Kadyrov, E.

1996-06-01

312

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

313

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

314

Airbreathing Pulse Detonation Engine Performance.  

National Technical Information Service (NTIS)

This paper presents performance results for pulse detonation engines (PDE) 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 b...

L. A. Povinelli S. Yungster

2002-01-01

315

Lightning Induced by Thermonuclear Detonations.  

National Technical Information Service (NTIS)

The lightning flashes induced by a thermonuclear detonation at Eniwetok Atoll in the Pacific in 1952 are described. The five discharges were upward-propagating and were apparently initiated from instrumentation stations slightly above sea level. The likel...

M. A. Uman D. F. Seacord G. H. Price E. T. Pierce

1971-01-01

316

Rotating Detonation Engine Operation (Preprint).  

National Technical Information Service (NTIS)

A Rotating Detonation Engine engineered and manufactured by Pratt and Whitney Seattle Aerosciences Center was loaned to the Air Force Research Laboratory at Wright-Patterson Air Force Base for further testing and development. The engine was originally des...

A. G. Naples F. R. Schauer J. A. Suchocki J. L. Hoke S. J. Yu

2012-01-01

317

Fine structure in nitromethane/acetone detonations  

SciTech Connect

Dark waves in the detonation front of nitromethane/acetone mixtures, known for 30 years, have been photographed using pairs of image intensifier cameras, triggered at slightly different times. The photographs show the motions and changes of the complex wave structure. Intriguing results are that the average brightness doesn't change as much from center to edge as simple theory would predict, and brightness goes down rather than up when a reflected shock from a glass plate enters the explosive products. The structure remains visible in the products stagnated against a glass plate, showing that the bright regions are high temperature regions, not just areas where less absorbing material is present ahead of the emitting layer.

Davis, W.C.

1981-01-01

318

Influence of diaphragm properties on shock wave transmission  

Microsoft Academic Search

One detonation initiation method currently being investigated for possible use in pulse detonation engines is the 'pre-detonator' or 'driver tube' concept. In this concept, a tube filled with sensitive fuel-oxygen mixture is spark ignited and the resulting detonation wave is used to transmit a strong shock wave to a larger tube containing relatively insensitive fuel-air mixture. The high initial shock

S. B. Murray; F. Zhang; K. B. Gerrard; P. Guillo; R. C. Ripley

2005-01-01

319

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

320

High-speed photography for pressure generation using the underwater explosion of spiral detonating cord  

NASA Astrophysics Data System (ADS)

In recent years we have devoted our efforts to the studies on the various shock processing techniques using explosives for the objectives of gaining materials with the good properties. Those techniques include the punch of pipes, shock consolidation of metallic and ceramic powders, explosive welding of amorphous ribbon on the steel or copper substrate, explosive engraving for the art objects and explosive forming of shells and spheres, and the improvement of the permeability of wood by shock wave. However, to a specific processing technique, it needs to control the shock wave for meeting the demands of that processing purpose. One important control is how to increase the strength of underwater shock wave. Therefore, we propose the following method to converge the underwater shock wave by putting a piece of detonating cord in a spiral way. First, the assignment of the spiral shape of detonation was determined from the geometrical consideration and the basic features of the detonation cord itself. Second, the converging process of the underwater shock wave from the explosion of such designed shape of detonating cord was photographically observed by using the high speed camera in the framing form. The spiral shape with the 100 mm distance from detonating start point to the center of the spiral (indicated by r1) was selected. They were amounted together with the electric detonator and the detonating cord. The photographs confirm that the underwater shock wave moves toward the spiral center in a convergence way. Third, the pressure nearing the spiral center was measured experimentally by means of the pressure transducers. The distance, Dh, between the detonating cord and the transducer was set to be 272 mm. Compared to the case that the detonating cord was placed in straight way, the maximum pressure in the case with the spiral shape is verified to be unchanged, but the impulse, however, is much improved. This reason may be due to over- greatly set Dh. When the distance Dh was set to 50 mm, the pressure measurement was made again and as a result, the large pressure value was record. Compared to the straightly placed detonating cord, it is shown that 3 times higher peak pressure is available in the spiral detonation cord. The results demonstrate that in a small range the pressure of underwater shock wave is indeed converged and higher pressure value is obtained.

Itoh, Shigeru; Nagano, Shirou; Hamada, Toru; Murata, Kenji; Kato, Yukio

2001-04-01

321

Numerical simulations of detonation transmission  

Microsoft Academic Search

The complex, dynamic shock-detonation structure formed by the glancing interaction of a primary detonation with a secondary explosive is studied using time-dependent two-dimensional simulations and related experiments. The materials considered in the simulations are stoichiometric and lean mixtures of hydrogen and oxygen diluted with argon. Related experiments have used undiluted hydrogen and oxygen as well as other gases. The conditions

Elaine S. Oran; David A. Jones; Martin Sichel

1991-01-01

322

Steady non-ideal detonations  

Microsoft Academic Search

Theories for determining the velocity of detonation (VoD) in highly non-ideal explosives, e.g. commercial explosives used in mining, are discussed. Such explosives have critical charge diameters of several centimetres. An analysis of the interaction between detonations and confining materials along the explosive-confiner interface reveals there a two main types of interaction. In the first (denoted here by case 1) the

Gary Sharpe

2009-01-01

323

LIGHTNING INDUCED BY THERMONUCLEAR DETONATIONS  

Microsoft Academic Search

The lightning flashes induced by a thermonuclear detonation at Eniwetok Atoll in the Pacific in 1952 are described. The five discharges were upward-propagating and were apparently initiated from instrumentation stations slightly above sea level. The likely mechanism for the necessary charge and electric-field generation (Compton electrons produced by gamma rays from the detonation) is explored quantitatively. The electric-field intensity calculated

M. A. Uman; D. F. Seacord; G. H. Price; E. T. Pierce; R. E. Holzer

1972-01-01

324

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

325

Response of LASL Detonators to A.C. Voltage.  

National Technical Information Service (NTIS)

Modern LASL detonators were subjected to three alternating current waveforms to determine the susceptibility of the detonators to high-order detonations when the line voltages supplied by local utility companies are applied across the detonator electrodes...

G. E. Round T. S. Chou J. R. Taylor

1978-01-01

326

Deflagration-to-detonation transition in inertial-confinement-fusion baseline targets  

SciTech Connect

By means of highly resolved one-dimensional hydrodynamics simulations, we provide an understanding of the burn process in inertial-confinement-fusion baseline targets. The cornerstone of the phenomenology of propagating burn in such laser-driven capsules is shown to be the transition from a slow unsteady reaction-diffusion regime of thermonuclear combustion (some sort of deflagration) to a fast detonative one. Remarkably, detonation initiation follows the slowing down of a shockless supersonic reaction wave driven by energy redeposition from the fusion products themselves. Such a route to detonation is specific to fusion plasmas.

Gauthier, P.; Chaland, F.; Masse, L. [Commissariat a l'Energie Atomique-Direction des Applications Militaires Ile de France, Boite Postale 12, 91680 Bruyeres le Chatel (France)

2004-11-01

327

Deflagration-to-detonation transition in inertial-confinement-fusion baseline targets.  

PubMed

By means of highly resolved one-dimensional hydrodynamics simulations, we provide an understanding of the burn process in inertial-confinement-fusion baseline targets. The cornerstone of the phenomenology of propagating burn in such laser-driven capsules is shown to be the transition from a slow unsteady reaction-diffusion regime of thermonuclear combustion (some sort of deflagration) to a fast detonative one. Remarkably, detonation initiation follows the slowing down of a shockless supersonic reaction wave driven by energy redeposition from the fusion products themselves. Such a route to detonation is specific to fusion plasmas. PMID:15600681

Gauthier, P; Chaland, F; Masse, L

2004-11-11

328

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

329

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

NASA Astrophysics Data System (ADS)

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 on the parameters of detonation combustion waves and accordingly on the cycle work, thermal efficiency, and specific parameters of pulse detonation engines have been performed. It has been established that the loss due to the irreversibility of the process of heat supply in detonation combustion waves is much lower when propulsion modules are installed in the heated-gas flow. It has been shown that the temperature of the working medium fed to propulsion modules is the determining factor influencing the thermodynamic efficiency of the detonation-fuel-combustion cycle. Generalized characteristics in the form of one-parameter dependences of the specific parameters of propulsion modules of pulse detonation engines on the temperature of the working medium fed to them have been obtained.

Nechaev, Yu. N.

2010-03-01

330

Detonation Initiation by Shock Reflection from an Orifice Plate  

NASA Astrophysics Data System (ADS)

Results from an experimental investigation of the interaction of a “non-ideal” shock wave and a single obstacle are reported. The shock wave is produced ahead of an accelerated flame in a 14 cm inner-diameter tube partially filled with orifice plates. The shock wave interacts with a single larger blockage orifice plate placed 15-45 cm after the last orifice plate in the flame acceleration section of the tube. Experiments were performed with stoichiometric ethylene-oxygen mixtures with varying amounts of nitrogen dilution at atmospheric pressure and temperature. The critical nitrogen dilution was found for detonation initiation. It is shown that detonation initiation occurs if the chemical induction time based on the reflected shock state is shorter than the time required for an acoustic wave to traverse the orifice plate upstream surface, from the inner to the outer diameter. The similarity between the present results and those obtained from previous investigators looking at detonation initiation by ideal shock reflection produced in a shock tube indicates that the phenomenon is not sensitive to the detailed structure of the shock front but only on the average shock strength.

Ciccarelli, G.; de Witt, B.

2006-07-01

331

Numerical and analytical studies of the dynamics of gaseous detonations  

NASA Astrophysics Data System (ADS)

This thesis examines two dynamic parameters of gaseous detonations, critical energy and cell size. The first part is concerned with the direct initiation of gaseous detonations by a blast wave and the associated critical energy. Numerical simulations of the spherically symmetric direct initiation event with a simple chemical reaction model are presented. Local analysis of the computed unsteady reaction zone structure identifies a competition between heat release rate, front curvature and unsteadiness. The primary failure mechanism is found to be unsteadiness in the induction zone arising from the deceleration of the shock front. On this basis, simplifying assumptions are applied to the governing equations, permitting solution of an analytical model for the critical shock decay rate. The local analysis is validated by integration of reaction zone structure equations with detailed chemical kinetics and prescribed unsteadiness. The model is then applied to the global initiation problem to produce an analytical equation for the critical energy. Unlike previous phenomenological models, this equation is not dependent on other experimentally determined parameters. For different fuel-oxidizer mixtures, it is found to give agreement with experimental data to within an order of magnitude. The second part of the thesis is concerned with the development of improved reaction models for accurate quantitative simulations of detonation cell size and cellular structure. The mechanism reduction method of Intrinsic Low-Dimensional Manifolds, originally developed for flame calculations, is shown to be a viable option for detonation simulations when coupled with a separate model in the induction zone. The agreement with detailed chemistry calculations of constant volume reactions and one-dimensional steady detonations is almost perfect, a substantial improvement on previous models. The method is applied to a two-dimensional simulation of a cellular detonation in hydrogen-oxygen-argon. The results agree well with an earlier detailed chemistry calculation and experimental data. The computational time is reduced by a factor of 15 compared with a detailed chemistry simulation.

Eckett, Christopher Adam

332

Numerical simulation of transient detonation structures in H2-O2 mixtures in smooth pipe bends  

Microsoft Academic Search

While the detailed structure of detonations in low-pressure hydrogen-oxygen mixtures with high argon dilution has been fairly well analyzed by means of numerical simulation for two-dimensional rectangular channels, open questions remain for three space dimensions and non-rectangular geometries. In the present paper, we simulate the transient structural evolution as Chapman-Jouguet detonation waves in a perfectly stirred 2 H2+O2+7 Ar mixture

Deiterding

2007-01-01

333

Analyses of Direct Detonation Initiation with Realistic Finite-Rate Chemistry  

Microsoft Academic Search

The present paper reports high-fidelity simulation of dir ect initiation processes of cylindrical detonation waves by concentrated energy deposition. The goal is to understand the underpinning mechanisms in failed or successful detonation initiation processes. We employed the Space-Time CESE method to solve the reacting flow equations, including realistic finite-rate chemistry model of the nine species and twenty-four reactions for H2-O2-Ar

Kyoung-Su Im; S.-T. John

334

Two-dimensional cellular structure of a kinetically unstable detonation front  

Microsoft Academic Search

Based on previously published results on the detonation of gaseous and liquid explosives, an explanation is given to the formation\\u000a of the two-dimensional cellular structure of the detonation front of some gas mixtures undergoing a two-step exothermic transformation\\u000a at the wave front and suggestions are proposed for the mechanism of development of the two-dimensional cellular structure\\u000a in the case of

A. N. Dremin

2008-01-01

335

DETONATION PRESSURE MEASUREMENTS ON PETN  

SciTech Connect

PETN is widely recognized as an example of nearly ideal detonation performance. The chemical composition is such that little or no carbon is produced in the detonation products. The reaction zone width is less than currently detectable. (<1 ns) Observations on PETN have thus become a baseline for EOS model predictions. It has therefore become important to characterize the detonation parameters as accurately as possible in order to provide the most exacting comparisons of EOS predictions with experimental results. We undertook a painstaking review of the detonation pressure measurements reported in an earlier work that was presented at the Fifth Detonation Symposium and found that corrections were required in determining the shock velocity in the PMMA witness material. We also refined the impedance calculation to account for the difference between the usual ''acoustic'' method and the more accurate Riemann integral. Our review indicates that the CJ pressures previously reported for full density PETN require an average lowering of about 6 percent. The lower densities require progressively smaller corrections. We present analysis of the records, supporting hydrodynamic simulations, the Riemann integral results, and EOS parameter values derived from the revised results.

Green, L G; Lee, E L

2006-06-23

336

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

337

Investigation of organic dust detonation in the presence of chemically inert particles  

SciTech Connect

The results of experimental studies of organic dust detonation in the presence of chemically inert particles are presented. Tests were carried out using a vertical detonation tube, and direct streak pictures showing the flame acceleration and pressure and temperature records were obtained. Flax dust, dispersed in an oxygen atmosphere, was used as the fuel, and two kinds of quartz sand were introduced as nonreacting particles. It was found that addition of inert particles caused a linear decrease of the detonation wave velocity but had no special influence on the transition distance. Calculations using the Gordon McBride Code showed that propagation of the detonation wave in a dust-oxygen mixture requires that the dust particles burnout at a level of about 70% but addition of inert particles increased the necessary burnout level to over 80% (with a significant decrease of the detonation wave velocity). The aim of this work was to investigate the processes of flame self acceleration and transition to detonation in mixtures of organic dust with oxygen and to investigate the influence of chemically neutral particles (used as a flame inhibiting agent) on these processes.

Klemens, R.; Kapuscinski, M.; Wolinski, M.; Wolanski, P. (Politechnika Warszawa (Poland). Instytut Techniki Cieplnej); Sichel, M. (Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering)

1994-12-01

338

Multidisciplinary Study of Pulse Detonation Engine Propulsion.  

National Technical Information Service (NTIS)

The Penn State-led MURI effort on Pulse Detonation Engine (PDE) research is detailed in this report. The multidisciplinary research effort brought together a team of leading researchers in the areas of the initiation and propagation of detonations, liquid...

R. J. Santoro V. Yang J. E. Shepherd C. K. Law

2003-01-01

339

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

340

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

341

Shock initiation and detonation properties of bisfluorodinitroethyl formal (FEFO)  

NASA Astrophysics Data System (ADS)

FEFO is a liquid explosive with a density of 1.60 g/cm3 and an energy output similar to that of trinitrotoluene (TNT), making it one of the more energetic liquid explosives. Here we describe shock initiation experiments that were conducted using a two-stage gas gun using magnetic gauges to measure the wave profiles during a shock-to-detonation transition. Unreacted Hugoniot data, time-to detonation (overtake) measurements, and reactive wave profiles were obtained from each experiment. FEFO was found to initiate by the homogeneous initiation model, similar to all other liquid explosives we have studied (nitromethane, isopropyl nitrate, hydrogen peroxide). The new unreacted Hugoniot points agree well with other published data. A universal liquid Hugoniot estimation slightly under predicts the measured Hugoniot data. FEFO is very insensitive, with about the same shock sensitivity as the triamino-trinitro-benzene (TATB)-based explosive PBX9502 and cast TNT.

Gibson, L. L.; Sheffield, S. A.; Dattelbaum, Dana M.; Stahl, David B.

2012-03-01

342

Structure of Detonations in Non-Ideal Stratified Explosives  

NASA Astrophysics Data System (ADS)

Stratified explosives are functionally-graded formulations in which the chemical and physical composition changes from point to neighboring point, but gradually. Introducing a gradient in the composition allows the formulator and warhead designer additional degrees of freedom beyond the scope of current uniform, traditional explosives. For example, the shape of the detonation wave can be controlled, directional effects can be directly built into the explosive itself, corner turning effects can be eliminated, etc. In the paper, the mathematical aspects of modeling the detonation in stratified explosives are introduced. In order to emphasize the structure of the wave, a simple model is used to propagate the reaction from point to point, without invoking the physics of ignition or growth of reaction, but the late release of energy in non-ideal explosives is properly incorporated into the reaction model.

Landsberg, Alexandra; Guirguis, Raafat

2001-06-01

343

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

344

Slag Characterization and Removal Using Pulse Detonation for Coal Gasification.  

SciTech Connect

The research activities performed in this quarter (reporting period: 07/01/97- 09/30/97) are summarized as follows: The research activities concentrated on (1) Design, development, and fabrication of a 9 positions (3x3 matrix form) fixture (2) Preparation of the test parameters (3) Multi-cycle detonation wave slag removal test (4) Partial analysis of the test results and (5) Interpretation and discussion of the test results.

Hugue, Z; Mei, D.; Biney, P.O.; Zhou, J.; Ali, M.R.

1997-09-25

345

Numerical Structure Analysis of Regular Hydrogen-Oxygen Detonations  

Microsoft Academic Search

Large-scale numerical simulations have been carried out to analyze the internal wave structure of a regular oscillating low-pressure H2 : O2 : Ar-Chapman-Jouguet detonation in two and three space-dimensions. The chemical reaction is modeled with a non-equilibrium mechanism that consists of 34 elementary reactions and uses nine thermally perfect gaseous species. A high local resolution is achieved dynami- cally at

Ralf Deiterding

2003-01-01

346

Fluid mechanics of pulse detonation thrusters  

NASA Astrophysics Data System (ADS)

The advantages of constant volume combustion cycle as compared to constant pressure combustion in terms of thermodynamic efficiency have focused the researches of advanced propulsion on detonation engines. The paper gives coverage of efforts undertaken during past decades in adjusting detonations for propulsion applications, and highlights new challenges in studying fluid flow dynamics relevant to onset of detonation.

Phylippov, Yu. G.; Dushin, V. R.; Nikitin, V. F.; Nerchenko, V. A.; Korolkova, N. V.; Guendugov, V. M.

2012-07-01

347

An efficient purification method for detonation nanodiamonds  

Microsoft Academic Search

This article reports the purification process of detonation soot to obtain pure nanodiamond powder. Nanodiamonds are synthesized by detonation using a high explosive mixture composed of trinitrotoluene and hexogen. The detonation of the charge leads to a powder containing nanodiamonds as well as metallic impurities and sp2 carbon species. Further, to remove metallic particles, an unusual acidic treatment (hydrofluoric\\/nitric acids;

V. Pichot; M. Comet; E. Fousson; C. Baras; A. Senger; F. Le Normand; D. Spitzer

2008-01-01

348

Equation of state for detonation product gases  

Microsoft Academic Search

A thermodynamic analysis procedure of the detonation product equation of state (EOS) together with the experimental data set of the detonation velocity as a function of initial density has been formulated. The Chapman-Jouguet (CJ) state [W. Ficket and W. C. Davis, Detonation: Theory and Experiment (University of California Press, Berkeley 1979)] on the p-nu plane is found to be well

Kunihito Nagayama; Shiro Kubota

2003-01-01

349

Detonation chemistry studies of energetic materials using laboratory scale samples  

SciTech Connect

We describe an apparatus by which the detonation products of an explosive can be identified and whose relative concentrations can be determined quantitatively. These measurements can be made on products that have been formed in less than one microsecond after the passage of the detonation wave. The technique is based on the rapid quenching of chemical reactions by virtue of the free expansion of the products into vacuum. Of course, products that have been formed over a longer period of time and under different pressure/temperature conditions can also be studied. Time resolved molecular-beam mass spectrometry is used, so that whether detonation occurred or not in forming the products can be determined. We describe optical techniques, principally Schlieren photographs, that also confirm detonation. We report measurements made on six standard explosives, PETN, RDX, HMX, HNS, TNT and TATB, and one research explosive, nitric oxide. For none of the standard explosives do we measure product distributions that agree with model predictions based on equilibrium assumptions. A computer model of the free expansion is described briefly and its importance to the interpretation of the data is emphasized. 16 refs., 13 figs.

Blais, N.C.; Greiner, N.R.; Fernandez, W.J.

1989-01-01

350

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

351

Asymmetry and the Nucleosynthetic Signature of Nearly Edge-lit Detonation in White Dwarf Cores  

NASA Astrophysics Data System (ADS)

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.; Meakin, Casey A.; Seitenzahl, Ivo R.; Truran, James W.

2012-01-01

352

Determination of the Velocity-Curvature Relationship for Unknown Detonation Front Shapes  

NASA Astrophysics Data System (ADS)

Detonation Shock Dynamics (DSD) is a surface propagation concept that replaces the detonation shock and reaction zone with a surface that evolves according to a specified normal-velocity evolution law. DSD is able to model detonation propagation when supplied with two components: the normal-detonation-velocity variation versus detonation surface curvature and the surface edge angle at the explosive-confiner interface. The velocity-curvature relationship is derived from experimental rate-stick data. Experimental front shapes can be fitted to an analytic equation with a similar characteristic shape and the detonation velocity-curvature relationship computed from that analytic expression. In some complex explosive-confiner configurations, an appropriate functional form for the detonation front shape may be difficult to construct. To address such situations, we numerically compute the velocity-curvature relationship directly from discrete experimental front-shape data with no assumptions of wave shape. The results are then compared to the analytic method for determining the velocity-curvature relationship. The possibilities and limitations of such an approach are discussed.

Jackson, Scott; Short, Mark

2011-06-01

353

Propagation of near-limit gaseous detonations in small diameter tubes  

NASA Astrophysics Data System (ADS)

In this study, detonation limits in very small diameter tubes are investigated to further the understanding of the near-limit detonation phenomenon. Three small diameter circular tubes of 1.8, 6.3, and 9.5 mm inner diameters, of 3 m length, were used to permit the near-limit detonations to be observed over long distances of 300 to 1500 tube diameters. Mixtures with high argon dilution (stable) and without dilution (unstable) are used for the experiments. For stable mixtures highly diluted with argon for which instabilities are not important and where failure is due to losses only, the limit obtained experimentally appears well to be in good agreement in comparison to that computed by the quasi-steady ZND theory with flow divergence or curvature term modeling the boundary layer effects. For unstable detonations it is suggested that suppression of the instabilities of the cellular detonation due to boundary conditions is responsible for the failure of the detonation wave. Different near-limit propagation regimes are also observed, including the spinning and galloping mode. Based on the present experimental results, an attempt is made to study an operational criterion for the propagation limits of stable and unstable detonations.

Camargo, Alexandra; Ng, Hoi Dick; Chao, Jenny; Lee, John H. S.

2010-12-01

354

Detonation Properties of Powdered Ammonium Nitrate  

NASA Astrophysics Data System (ADS)

It was studied the parameters of detonation of Ammonium Nitrate (powder) The detonation properties of industrial explosive Ammonite 6 which is mixture of TNT 20% and AN 80% and THT powdered were compared. By using the known formula for detonation characteristic of the mixture of different HE it was estimated that the upper limit of detonation of AN by itself must be not less than 5 km per sec. The large-scale experiments with plane charges of AN with the thickness of layer of AN 200mm were made. The measured detonation velocity appeared to be 5 km per sec.

Deribas, Andrei A.; Simonov, Valery A.

1999-06-01

355

High-Temperature EBW Detonators.  

National Technical Information Service (NTIS)

A high-temperature-resistant exploding bridgewire detonator is described. The explosive is BTX, which shows no exotherm below the melting point 263 exp 0 C, and is stable in vacuum stability tests at a temperature exposure of at least 175 exp 0 C for 90 d...

R. H. Dinegar L. A. Carlson M. D. Coburn

1976-01-01

356

Slang characterization and removal using pulse detonation technology during coal gasification  

SciTech Connect

Boiler slagging and fouling as a result of inorganic impurities in combustion gases being deposited on heat transfer tubes have caused severe problems in coal-fired power plant operation. These problems are fuel, system design, and operating condition dependent. Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. The detonation wave technique based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. These detonation waves have been demonstrated experimentally to have exceptionally high shearing capability important to the task of removing slag and fouling deposits. The experimental results show that the single shot detonation wave is capable of removing the entire slag (types of slag deposited on economizer) even at a distance of 8 in. from the exit of a detonation engine tube. Wave strength and slag orientation also have different effects on the chipping off of the slag. This paper discusses about the results obtained in effectively removing the economizer slag.

Huque, Z.; Mei, D.; Biney, P.O.; Zhou, J.

1997-03-25

357

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

358

Successive detonations in accreting white dwarfs as an alternative mechanism for type I supernovae  

SciTech Connect

Simulations of exploding helium shells in accreting white dwarfs show that the ingoing shock wave is strong enough to ignite the carbon at the center into an outgoing detonation wave. This mechanism provides a new way to form supernovae of type Ia, not only in heavy white dwarfs approaching the Chandrasekhar mass, but in a much wider range of masses. Thus, many of the problems which arise in current models, such as deflagration versus detonation, may be solved as explosions of white dwarfs of lesser mass are considered. 30 refs.

Livne, E. (Jerusalem Hebrew Univ. (Israel))

1990-05-01

359

2D simulations of the double-detonation model for thermonuclear transients from low-mass carbon-oxygen white dwarfs  

Microsoft Academic Search

Thermonuclear explosions may arise in binaries in which a CO white dwarf (WD) accretes He from a companion. If the accretion rate allows a sufficiently large mass of He to accumulate prior to ignition of nuclear burning, the He surface layer may detonate, giving rise to an astrophysical transient. Detonation of the He layer generates shock waves that propagate into

S. A. Sim; M. Fink; M. Kromer; F. K. Roepke; A. J. Ruiter; W. Hillebrandt

2011-01-01

360

Detonator Performance Characterization Using Multi-Frame Laser Schlieren Imaging  

Microsoft Academic Search

Several experiments that are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation to full detonation to transition to booster and booster detonation will be presented. High speed laser schlieren movies have been used to study several explosive initiation events, such as exploding bridgewires (EBW), exploding foil initiators

S. A. Clarke; C. D. Landon; M. J. Murphy; M. E. Martinez; T. A. Mason; K. A. Thomas

2009-01-01

361

DETONATOR PERFORMANCE CHARACTERIZATION USING MULTI-FRAME LASER SCHLIEREN IMAGING  

Microsoft Academic Search

Several experiments that are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation to full detonation to transition to booster and booster detonation will be presented. High speed laser schlieren movies have been used to study several explosive initiation events, such as exploding bridgewires (EBW), exploding foil initiators

S. A. Clarke; C. D. Landon; M. J. Murphy; M. E. Martinez; T. A. Mason; K. A. Thomas

2009-01-01

362

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

363

Detonation and Pulse Detonation Engines 1999-2005 (CD-ROM).  

National Technical Information Service (NTIS)

Research carried out from 2003-2005 at the Explosion Dynamics Laboratories at Caltech under an ONR contract has examined many issues critical to Pulse Detonation Engine (PDE) development. These include: detonation structure imaging using OH PLIF; a narrow...

2005-01-01

364

Study on the Mechanism of Detonation to Quasi-detonation Transition  

NASA Astrophysics Data System (ADS)

In this paper, the mechanism of detonation to quasi-detonation transition was discussed, a new physical model to simulate quasi-detonation was proposed, and one-dimensional theoretical and numerical simulation was conducted. This study firstly demonstrates that the quasi-detonation is of thermal choking. If the conditions of thermal choking are created by some disturbances, the supersonic flow is then unable to accept additional thermal energy, and the CJ detonation becomes the unstable quasi-detonation precipitately. The kinetic energy loss caused by this transition process is firstly considered in this new physical model. The numerical results are in good agreement with previous experimental observations qualitatively, which demonstrates that the quasi-detonation model is physically correct and the study are fundamentally important for detonation and supersonic combustion research.

Liu, Yun-Feng; Jiang, Zong-Lin

2010-05-01

365

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

366

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

367

A lecture on detonation-shock dynamics  

SciTech Connect

We summarize recent investigations into the theory of multi-dimensional, time-dependent detonation. These advances have led to the development of a theory for describing the propagation of high-order detonation in condensed-phase explosives. The central approximation in the theory is that the detonation shock is weakly curved. Specifically, we assume that the radius of curvature of the detonation shock is large compared to a relevant reaction-zone thickness. Our main findings are: (1) the flow is quasi-steady and nearly one dimensional along the normal to the detonation shock; and (2) the small deviation of the normal detonation velocity from the Chapman-Jouguet (CJ) value is generally a function of curvature. The exact functional form of the correction depends on the equation of state (EOS) and the form of the energy-release law. 8 refs.

Stewart, D.S.; Bdzil, J.B.

1987-01-01

368

Incomplete Carbon Detonations in Thermonuclear Supernovaefootnotemark  

NASA Astrophysics Data System (ADS)

All explosion models proposed up to date for thermonuclear supernovae involve carbon-oxygen detonations at low densities. At these densities Si and O time-scales of burning become comparable or longer than hydrodynamical time-scales and only C burning may occur (C-detonation). Therefore, burning is not complete and intermediate mass elements are produced as observed in the near-maximum spectra. However, previous analysis of the structure and stability of detonations in thermonuclear supernovae did not consider incomplete detonations with partial energy release. In this work we find that, in contrast with complete detonations, C-detonations are highly unstable and may quench at low densities. Implications for supernova modelling and observations are discussed.

Domínguez, I.; Khokhlov, A.

2012-07-01

369

Detonation of propane-air mixtures under injection of hot detonation products  

Microsoft Academic Search

The tube for spontaneous detonation (Institute of Technical Physics, Russian Federal Nuclear Center, Snezhinsk) was used to\\u000a study the initiation and development of detonation in propane-air mixtures under injection of hot detonation products into\\u000a them. The full picture of this phenomenon was recorded: the injection of hot detonation products into the main tube of the\\u000a facility with the formation of

V. I. Tarzhanov; I. V. Telichko; V. G. Vil’danov; V. I. Sdobnov; A. E. Makarov; S. L. Mukhin; I. G. Koretskii; V. A. Ogarkov; V. V. Vlasov; A. D. Zinchenko; A. V. Vorob’ev; A. N. Grachev; V. A. Matkin; V. A. Potashnikov

2006-01-01

370

Quantic Industries Inc. slapper detonator performance  

Microsoft Academic Search

Under the Lawrence Livermore National Laboratories (LLNL) Small Business Technology Transfer Program, assistance was given to Quantic Industries Inc. to use the High Explosive Applications Facility (HEAF), its apparatus, and LLNL expertise to characterize the performance of Quantic`s micro-clad copper\\/kapton slapper detonator assemblies and establish their threshold to detonate HNS-IV. The project involved measuring the performance of these slapper detonators,

J. L. Cutting; R. S. Lee; R. L. Hodgin

1994-01-01

371

Power and phase spectra for detonating cord  

SciTech Connect

A simple mathematical model is presented for a detonating cord seismic source. This model can be used for most configurations of detonating cord. Power and phase spectra are calculated. Numerical results are presented for a straight strand detonated in the center. Time delays associated with the initiation of vertically travelling energy at low frequencies can be determined from the phase spectra. 2 references, 5 figures.

Burkhard, N.R.

1983-11-01

372

Deflagrations and Detonations in Thermonuclear Supernovae  

Microsoft Academic Search

We study a type Ia supernova explosion using three-dimensional numerical simulations based on reactive fluid dynamics. We consider a delayed-detonation model that assumes a deflagration-to-detonation transition. In contrast with the pure deflagration model, the delayed-detonation model releases enough energy to account for a healthy explosion, and does not leave carbon, oxygen, and intermediate-mass elements in central parts of a white

Vadim N. Gamezo; Alexei M. Khokhlov; Elaine S. Oran

2004-01-01

373

Detonation Limit Thresholds in H2\\/O2 Rotating Detonation Engine  

Microsoft Academic Search

The rotating detonation engine (RDE) is a new engine system using detonation, which may provide a higher performance and smaller and simpler design in comparison with the pulse detonation engine (PDE) and other traditional engines. However the research on RDE stands just at the first step now. The authors perform a numerical analysis to understand about RDE in terms of

Takayuki Yamada; A. Koichi Hayashi; Eisuke Yamada; Nobuyuki Tsuboi; Venkat E. Tangirala; Toshi Fujiwara

2010-01-01

374

Detonation Branching in a PDE with Liquid Hydrocarbon Fuel.  

National Technical Information Service (NTIS)

A pulse detonation engine (PDE) capitalizes on the large mass flux and pressure rise associated with detonations to create thrust, which is proportional to PDE cycle frequency. This research showed that using a branched detonation as an ignition source, a...

K. L. Panzenhagen

2004-01-01

375

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Compatibility of electric detonators. 56.6400 Section 56...METAL AND NONMETAL MINES Explosives Electric Blasting § 56.6400 Compatibility of electric detonators. All electric detonators...

2013-07-01

376

Deflagrations and detonations in thermonuclear supernovae.  

PubMed

We study a type Ia supernova explosion using three-dimensional numerical simulations based on reactive fluid dynamics. We consider a delayed-detonation model that assumes a deflagration-to-detonation transition. In contrast with the pure deflagration model, the delayed-detonation model releases enough energy to account for a healthy explosion, and does not leave carbon, oxygen, and intermediate-mass elements in central parts of a white dwarf. This removes the key disagreement between simulations and observations, and makes a delayed detonation the mostly likely mechanism for type Ia supernovae. PMID:15245271

Gamezo, Vadim N; Khokhlov, Alexei M; Oran, Elaine S

2004-05-28

377

Radioactive Fallout from Terrorist Nuclear Detonations  

SciTech Connect

Responding correctly during the first hour after a terrorist nuclear detonation is the key to reducing casualties from a low-yield surface burst, and a correct response requires an understanding of the rapidly changing dose rate from fallout. This report provides an empirical formula for dose rate as a function of time and location that can guide the response to an unexpected nuclear detonation. At least one post-detonation radiation measurement is required if the yield and other characteristics of the detonation are unknown.

Marrs, R E

2007-05-03

378

Dynamics of oblique detonations in ram accelerators  

NASA Astrophysics Data System (ADS)

Time-accurate numerical simulations are used to study the dynamic development of oblique detonations on accelerating projectiles in ram accelerators. These simulations show that the oblique detonation can be stabilized on the projectile. The high pressure generated behind the detonation can result in accelerations up to 106G and propel the projectile to velocities higher than 4.0 km/s. The detonation structure on the projectile is sensitive to the projectile geometry. A small change in the projectile shape is sufficient to alter the overall detonation structure and significantly affect the pressure distribution on the projectile. In order to maximize the thrust, an appropriate projectile shape has to be chosen to generate the detonation structure just behind the widest part of the projectile body. The projectile acceleration also has strong effects on the flow field and the detonation structure. During the acceleration, the location of the oblique detonation moves upstream from one reflected shock to another. However, one the detonation is stabilized behind the upstream shock, it remains at the new location until the transition to the next upstream shock occurs. In the simulations, the Non-Inertial-Source (NIS) technique was used to accurately represent of the projectile acceleration. Also, the Virtual-Cell-Embedding (VCE) method was employed to efficiently treat the complex projectile geometry on cartesian grids.

Li, Chiping; Kailasanath, K.; Oran, E. S.; Landsberg, A. M.; Boris, J. P.

1995-06-01

379

The effect of voide size on the detonation pressure of emulsion explosives.  

NASA Astrophysics Data System (ADS)

Ammonium nitrate-based emulsion explosive show non-ideal detonation behavior. Voids included in the emulsion explosives affect the non-idealdetonation behavior. The effects of voide size on the detonation pressure of emulsion explosives were studied experimentally. Detonation pressure was measured for the emulsion explosives sensitized with resin balloons of five different size ranging from 0.05mm to 2.42mm in average diameter, using PVDF pressure sensor. Pressure profile of emulsion explosives containing resin balloon of 0.05mm in average diamater shows von Neumann spike and pressure decay in reaction zone followed by Taylor wave. Pressure profile of emulsion explosive containing larger balloons present gradual pressure rise in detonation front due to front curvature and front perturvation caused by large voids. The comparison between the measured detonation pressure and calculated detonation pressure indicates that the fraction of ammonium nitrate reacted in reaction zone is higher than 80containing resin balloons of 0.05mm in diameter, and as low as 302.42mm in diameter. It was shown that reaction zone length is strongly affected by void size.

Hirosaki, Yoshikazu; Murata, Kenji; Kato, Yukio; Itoh, Shigeru

2001-06-01

380

Direct Calculation of Spherical Detonation Initiation of H2\\/O2\\/Ar Mixtures by the CESE Method  

Microsoft Academic Search

This paper reports high-fidelity simulation of the direct initiation process of spherical detonation waves by depositing various amounts of concentrated energy at the center of the explosion. The goal is to understand the underpinning mechanisms of failed or successful detonation initiation processes. One-dimensional reactive Euler equations including multiple species are solved by the Space-Time Conservation Element and Solution Element (CESE)

Bao Wang; S.-T. John

381

Double-detonation supernovae of sub-Chandrasekhar mass white dwarfs  

NASA Astrophysics Data System (ADS)

Type Ia supernovae are believed to be white dwarfs disrupted by a thermonuclear explosion. Here we investigate the scenario in which a rather low-mass, carbon-oxygen (C + O) white dwarf accumulates helium on its surface in a sufficient amount for igniting a detonation in the helium shell before the Chandrasekhar mass is reached. In principle, this can happen on white dwarfs accreting from a non-degenerate companion or by merging a C + O white dwarf with a low-mass helium one. In this scenario, the helium detonation is thought to trigger a secondary detonation in the C + O core. It is therefore called the “double-detonation sub-Chandrasekhar” supernova model. By means of a set of numerical simulations, we investigate the robustness of this explosion mechanism for generic 1-{M_?} models and analyze its observable predictions. Also a resolution dependence in numerical simulations is analyzed. Hydrodynamic simulations of the double-detonation sub-Chandrasekhar scenario are conducted in two and three spatial dimensions. The propagation of thermonuclear detonation fronts, both in helium and in the carbon-oxygen mixture, is computed by means of both a level-set function and a simplified description for nuclear reactions. The decision whether a secondary detonation is triggered in the white dwarf's core or not is made based on criteria given in the literature. In a parameter study involving different initial flame geometries for He-shell masses of 0.2 and 0.1 {M_?} (and thus 0.8 and 0.9 {M_?} of C + O), we find that a secondary detonation ignition is a very robust process. Converging shock waves originating from the detonation in the He shell generate the conditions for a detonation near the center of the white dwarf in most of the cases considered. Finally, we follow the complete evolution of three selected models with 0.2 {M_?} of He through the C/O-detonation phase and obtain 56Ni-masses of about 0.40 to 0.45 {M_?}. Although we have not done a complete scan of the possible parameter space, our results show that sub-Chandrasekhar models are not good candidates for normal or sub-luminous type Ia supernovae. The chemical composition of the ejecta features significant amounts of 56Ni in the outer layers at high expansion velocities, which is inconsistent with near-maximum spectra.

Fink, M.; Hillebrandt, W.; Röpke, F. K.

2007-12-01

382

Experimental study of detonating gas bubble oscillations using a shock tube  

Microsoft Academic Search

Oscillations of bubbles containing a mixture of a detonating gas with argon in their interior are studied. The bubbles are excited for oscillations by a pressure step generated in a shock tube. A bubble wall motion is observed by a rotating mirror camera and a radiated pressure wave by a needle hydrophone. For weak pressure steps the bubble behaves as

K. Vokurka

1993-01-01

383

Detonation chemistry: diffusion control in non-ideal explosives. [NHâNOâ and TNT  

Microsoft Academic Search

The performance of an explosive is a function of both the peak energy released near the detonation front, and the remainder of the energy that is released during the Taylor wave. The relative partitioning of energy between the front and the expansion, and the rate of energy release in the latter, may be controlled by either chemical kinetic or diffusion

R. R. McGuire; D. L. Ornellas; I. Akst

1978-01-01

384

Exploding bridge wire detonator with shock reflector for oil well usage  

Microsoft Academic Search

For use in a downhole oil tool exposed to high temperatures, a bridge wire detonator comprising: (a) a two electrode electric current system connected to a sacrificial bridge element thereacross for creating a momentary, electrically initiated initial shock wave therefrom; (b) a solid mass of high temperature stable secondary explosive sufficiently contacted with the bridge element to receive a substantial

J. O. Johnson; J. M. Barker; S. M. Reid

1988-01-01

385

Some perspectives on pulse detonation propulsion systems  

Microsoft Academic Search

Pulse detonation engines and rockets (PDE\\/Rs) can potentially revolutionize air breathing and rocket propulsion [1-6]. While the PDE concept is over five decades old, it has recently enjoyed renewed interest, due mostly to theoretical and computational studies indicating high cycle efficiencies. When modeled by a constant volume, Humphrey cycle, the detonation engine is found to be superior to that of

F. K. Lu; D. R. Wilson

2005-01-01

386

Initial Studies of the Pulse Detonation Engine.  

National Technical Information Service (NTIS)

In this report, it is verified that the Pulse Detonation Engine - the PDE - indeed has to potential of reaching a high specific impulse under the assumption that two key issues can be resolved - the initiation of the detonation and the problems involved i...

J. K. Tegner

1998-01-01

387

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

388

Using Schlieren Visualization to Track Detonator Performance  

NASA Astrophysics Data System (ADS)

Several experiments will be presented that are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation, to full detonation, to transition, to booster and booster detonation. High-speed multiframe schlieren imagery has been used to study several explosive initiation events, such as exploding bridgewires (EBWs), exploding foil initiators (EFIs or ``slappers''), direct optical initiation (DOI), and electrostatic discharge. Additionally, a series of tests has been performed on ``cut-back'' detonators with varying initial pressing heights. We have also used this diagnostic to visualize a range of EBW, EFI, and DOI full-up detonators. Future applications to other explosive events, such as boosters and insensitive high explosives booster evaluation, will be discussed. The EPIC finite element code has been used to analyze the shock fronts from the schlieren images to solve iteratively for consistent boundary or initial conditions to determine the temporal-spatial pressure profile across the output face of the detonator.

Clarke, S. A.; Bolme, C. A.; Murphy, M. J.; Landon, C. D.; Mason, T. A.; Adrian, R. J.; Akinci, A. A.; Martinez, M. E.; Thomas, K. A.

2007-12-01

389

Using Schlieren Visualization to Track Detonator Performance  

NASA Astrophysics Data System (ADS)

Several experiments that are part of a phased plan to understand the evolution of detonation in a detonator from initiation shock through run to detonation to full detonation to transition to booster and booster detonation will be presented. High Speed Laser Schlieren Movies have been used to study several explosive initiation events, such as exploding bridgewires (EBW), Exploding Foil Initiators (EFI) (or slappers), Direct Optical Initiation (DOI), and ElectroStatic Discharge (ESD). Additionally, a series of tests have been performed on ``cut-back'' detonators with varying initial pressing (IP) heights. We have also used this diagnostic to visualize a range of EBW, EFI, and DOI full-up detonators. Future applications to other explosive events such as boosters and IHE booster evaluation will be discussed. EPIC Hydrodynamic code has been used to analyze the shock fronts from the Schlieren images to reverse calculate likely boundary or initial conditions to determine the temporal-spatial pressure profile across the output face of the detonator. LA-UR-07-1229

Clarke, Steven; Thomas, Keith; Martinez, Michael; Akinci, Adrian; Murphy, Michael; Adrian, Ronald

2007-06-01

390

Hydraulic Resistance and Multiplicity of Detonation Regimes  

Microsoft Academic Search

The paper considers the effect of hydraulic resistance on detonation of gaseous premixtures. It is shown that the multiplicity of detonation regimes occasionally observed for explosions in rough tubes and in inert porous media may be successfully described in the framework of Zeldovich's (1940) quasi-one-dimensional formula- tion, provided the class of admissible solutions is not restricted exclusively to the solutions

G. SIVASHINSKY

391

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

392

Modeling of Non-Ideal Aluminized Detonations  

Microsoft Academic Search

We have implemented a Wood-Kirkwood (WK) kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions, while other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. Within the context of WK theory, we study the chemical interaction between Al and HMX detonation

W. Michael Howard; Laurence E. Fried; P. Clark Souers

1999-01-01

393

Oscillatory Behavior of Detonating Solid Explosives.  

National Technical Information Service (NTIS)

The report shows that the structural phenomenology of gaseous detonations is extendable to solid explosives of military interest. The cell size in gaseous detonations is a function of the effective heat release rate, i.e., that heat release rate experienc...

G. Melani P. M. Howe

1972-01-01

394

Deflagration to Detonation Transition in Thermonuclear Supernovae  

Microsoft Academic Search

We derive the criteria for deflagration to detonation transition (DDT) in a Type Ia supernova. The theory is based on the two major assumptions: (1) detonation is triggered via the Zeldovich gradient mechanism inside a region of mixed fuel and products, (2) the mixed region is produced by a turbulent mixing of fuel and products either inside an active deflagration

A. M. Khokhlov; E. S. Oran; J. C. Wheeler

1996-01-01

395

Deflagration to detonation transition in thermonuclear supernovae  

Microsoft Academic Search

The authors derive the criteria for deflagration to detonation transition (DDT) in a Type Ia supernova. The theory is based on the two major assumptions: (i) detonation is triggered via the Zeldovich gradient mechanism inside a region of mixed fuel and products, (ii) the mixed region is produced by a turbulent mixing of fuel and products either inside an active

A. M. Khokhlov; E. S. Oran; J. Craig Wheeler

1996-01-01

396

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

397

Initiation of Detonation in Various Gas Mixtures.  

National Technical Information Service (NTIS)

For the transition of a flame to a detonation the initiation distance, X(o), and the initiation time, t(D), have been measured for various detonable gas mixtures, and from these two quantities the Oppenheim velocity, V(Opp) = X(D)/t(D) has been obtained. ...

D. Pawel H. Vasatko H. G. Wagner P. J. Van Tiggelen

1970-01-01

398

Explosion and detonation characteristics of dimethyl ether  

Microsoft Academic Search

In this study, the explosion and detonation characteristics of dimethyl ether (DME) were experimentally investigated. A spherical pressure vessel with an internal volume of 180L was used as the explosion vessel. Therefore, tubes 10m in length with internal diameters of 25mm and 50mm were used as detonation tubes. In addition, we compared the characteristics of DME with those of propane

Toshio Mogi; Sadashige Horiguchi

2009-01-01

399

Statistical Hotspot Model for Explosive Detonation  

Microsoft Academic Search

The presence and need for energy localization in the ignition and detonation of high explosives is a corner stone in our understanding of explosive behavior. This energy localization, known as hot spots, provides the match that starts the energetic response that is integral to the detonation. In our model, we use the life cycle of a hot spot to predict

Albert Nichols

2005-01-01

400

An Outline of a Theory of Detonators  

Microsoft Academic Search

FURTHER to the reported property of silver formate of detonating at 85-90°1, it is perhaps opportune to offer some commentary on the nature of detonators in general. They are commonly derived from acids, the anions of which are the repositories of considerable stores of energy. This is liberated when the anions are discharged and the radicals, thus initially produced, decompose.

J. Kenner

1949-01-01

401

Spontaneous Formation of Detonations by Turbulent Flames in Thermonuclear Supernovae  

NASA Astrophysics Data System (ADS)

Presently, the scenario best capable of explaining the observational properties of "normal" type Ia supernovae (SNIa), which are of primary importance for cosmology, is the delayed-detonation model. This model postulates that a subsonic thermonuclear deflagration, which originates close to the center of a Chandrasekhar-mass white dwarf (WD) in a single-degenerate binary system, transitions to a supersonic detonation (deflagration-to-detonation transition, or DDT) during the later stages of the explosion. Modern large-scale multidimensional simulations 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. Significant progress has been made over the years in elucidating the nature of DDT in terrestrial confined systems with walls, obstacles, or pre-existing shocks. It remains unclear, however, whether and how a detonation can form in an unpressurized, unconfined system such as the interior of a WD. Here we show, through first-principles numerical simulations, that sufficiently fast, but subsonic, turbulent flames in such unconfined environments are inherently susceptible to DDT. The associated mechanism is based on the unsteady evolution of turbulent flames faster than the Chapman-Jouguet deflagrations and is qualitatively different from the traditionally suggested gradient (spontaneous reaction wave) model. It also does not require the formation of distributed flames. The proposed mechanism predicts the DDT density in SNIa to be 107 g/cm3, in agreement with the values previously found to give the best match with observations. This DDT mechanism opens the possibility for eliminating the transition density as a free parameter and, thus, for developing fully self-consistent global multidimensional SNIa models. This work was supported in part by the Naval Research Laboratory, the Air Force Office of Scientific Research, and by the Department of Defense High Performance Computing Modernization Program.

Poludnenko, Alexei Y.; Oran, E. S.

2012-01-01

402

Explosive Wave Shaper.  

National Technical Information Service (NTIS)

An explosive wave shaping system or wave shaper is disclosed. A 'flying' plate or disk of uniform thickness between the donor explosive and the acceptor explosive. The plate is driven against the acceptor explosive with sufficient force to detonate it. Th...

T. P. Liddiard

1965-01-01

403

Attosecond Shock Waves  

NASA Astrophysics Data System (ADS)

Shock-wave formation is a generic scenario of wave dynamics known in nonlinear acoustics, fluid dynamics, astrophysics, seismology, and detonation physics. Here, we show that, in nonlinear optics, remarkably short, attosecond shock transients can be generated through a strongly coupled spatial and temporal dynamics of ultrashort light pulses, suggesting a pulse self-compression scenario whereby multigigawatt attosecond optical waveforms can be synthesized.

Zhokhov, P. A.; Zheltikov, A. M.

2013-05-01

404

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

405

Joining of alumina and steel by a laser supported brazing process  

Microsoft Academic Search

A laser supported method to join ceramic materials with metals has been studied. Using a CO2-laser and an active braze filler material, Al2O3-ceramics have been brazed to steel. The microstructure of the interface has been examined and also the mechanical strength of the brazed joint using bending tests. Typical processing times are of the order of several minutes, which is

M. Rohde; I. Südmeyer; A. Urbanek; M. Torge

2009-01-01

406

Slag characterization and removal using pulse detonation for coal gasification. Quarterly research report, July 1--September 31, 1996  

SciTech Connect

Boiler slagging and fouling as a result of inorganic impurities in combustion gases being deposited on heat transfer tubes have caused severe problems in coal-fired power plant operation. These problems are fuel, system design, and operating condition dependent. Conventional slag and ash removal methods include the use of in situ blowing or jet-type devices such as air or steam soot blowers and water lances. Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. The detonation wave technique based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. These detonation waves have been demonstrated experimentally to have exceptionally high shearing capability important to the task of removing slag and fouling deposits. Several tests have been performed with single shot detonation wave at University of Texas at Arlington to remove the slag deposit. To hold the slag deposit samples at the exit of detonation tube, two types of fixture was designed and fabricated. They are axial arrangement and triangular arrangement. The slag deposits from the utility boilers have been used to prepare the slag samples for the test. The experimental results show that the single shot detonation wave is capable of removing the entire slag (types of slag deposited on economizer, and air-heater, i.e., relatively softer slags) and 30% of the reheater slag (which is harder) even at a distance of 6 in. from the exit of a detonation engine tube. Wave strength and slag orientation also have different effects on the chipping off of the slag. The annual report discusses about the results obtained in effectively removing the slag.

Huque, Z.; Mei, D.; Biney, P.O.; Zhou, J.; Ali, M.R.

1996-10-25

407

2D simulations of the double-detonation model for thermonuclear transients from low-mass carbon-oxygen white dwarfs  

NASA Astrophysics Data System (ADS)

Thermonuclear explosions may arise in binary star systems in which a carbon-oxygen (CO) white dwarf (WD) accretes helium-rich material from a companion star. If the accretion rate allows a sufficiently large mass of helium to accumulate prior to ignition of nuclear burning, the helium surface layer may detonate, giving rise to an astrophysical transient. Detonation of the accreted helium layer generates shock waves that propagate into the underlying CO WD. This might directly ignite a detonation of the CO WD at its surface (an edge-lit secondary detonation) or compress the core of the WD sufficiently to trigger a CO detonation near the centre. If either of these ignition mechanisms works, the two detonations (helium and CO) can then release sufficient energy to completely unbind the WD. These 'double-detonation' scenarios for thermonuclear explosion of WDs have previously been investigated as a potential channel for the production of Type Ia supernovae from WDs of ˜ 1 M?. Here we extend our 2D studies of the double-detonation model to significantly less massive CO WDs, the explosion of which could produce fainter, more rapidly evolving transients. We investigate the feasibility of triggering a secondary core detonation by shock convergence in low-mass CO WDs and the observable consequences of such a detonation. Our results suggest that core detonation is probable, even for the lowest CO core masses that are likely to be realized in nature. To quantify the observable signatures of core detonation, we compute spectra and light curves for models in which either an edge-lit or compression-triggered CO detonation is assumed to occur. We compare these to synthetic observables for models in which no CO detonation was allowed to occur. If significant shock compression of the CO WD occurs prior to detonation, explosion of the CO WD can produce a sufficiently large mass of radioactive iron-group nuclei to significantly affect the light curves. In particular, this can lead to relatively slow post-maximum decline. If the secondary detonation is edge-lit, however, the CO WD explosion primarily yields intermediate-mass elements that affect the observables more subtly. In this case, near-infrared observations and detailed spectroscopic analysis would be needed to determine whether a core detonation occurred. We comment on the implications of our results for understanding peculiar astrophysical transients including SN 2002bj, SN 2010X and SN 2005E.

Sim, S. A.; Fink, M.; Kromer, M.; Röpke, F. K.; Ruiter, A. J.; Hillebrandt, W.

2012-03-01

408

Formation of detonation in a pulse combustion chamber with a porous obstacle  

NASA Astrophysics Data System (ADS)

A study has been made of the influence of a porous obstacle on deflagration-to-detonation transition in a pulse combustion chamber of small length. Dependences of the detonation-wave velocity on the distance have been obtained for two samples of a porous material (steel spheres and a ceramic porous body). It has been shown that the use of an insert from a porous material leads to a reduction of 40% in the predetonation distance without changing substantially the structure of the pulse combustion chamber.

Alhussan, Kh.; Assad, M. S.; Penyazkov, O. G.; Sevruk, K. L.

2012-09-01

409

Spectroscopic studies of detonating heterogeneous explosives. [HNS  

SciTech Connect

The experimental objectives of this work are to use real-time spectroscopic techniques, emission spectroscopy and Raman spectra to monitor chemical and physical changes in shock-loaded or detonating high explosive (HE) samples. The investigators hope to identify chemical species including any transient intermediates. Also, they wish to determine the physical state of the material when the reactions are taking place; measure the temperature and the pressure; and study the effect of different initiation parameters and bulk properties of the explosive material. This work is just part of the effort undertaken to gain information on the detailed chemistry involved in initiation and detonation. In summary, the investigators have obtained vibrational temperatures of some small radical products of detonation, which may correlate with the detonation temperature. They have also observed that NO/sub 2/ is an early product from detonating HNS and RDX, and that other electronically excited radical species such as CN(B) are formed in HNS detonations. In the Raman work, the single-pulse spectra could be obtained even in the severe environment of a detonation, and that the rate of removal of the parent molecule could be monitored. 2 refs., 6 figs.

Renlund, A.M.; Trott, W.M.

1985-01-01

410

Shock Initiation and Detonation Properties of Bis-fluorodinitroethyl formal (FEFO)  

NASA Astrophysics Data System (ADS)

FEFO is a liquid explosive with a density of 1.6 g/cm^3 and an energy output somewhat higher than trinitrotoluene (TNT), making it one of the more energetic liquid explosives. Shock initiation experiments were conducted on a two-stage, gas gun using magnetic gauges to measure the wave profiles during a shock-to-detonation transition. Both unreacted Hugoniot data, as well as run-to-detonation measurements were obtained, along with the reactive wave profiles. FEFO was found to initiate by the homogeneous initiation model, as do all other liquid explosives we have studied. The new unreacted Hugoniot points agree with other published data and a universal liquid Hugoniot estimates the Hugoniot data quite well. It is quite insensitive, with about the same shock sensitivity as the triamino-trinitro-benzene-based explosives PBX9502 and LX-17. In addition to the shock initiation experiments, one experiment was done on the gun providing a reasonably accurate detonation velocity and a detonation wave profile. These are compared to the waveforms from the in-situ magnetic gauges, as well as to other data available in the literature.

Gibson, L. L.; Sheffield, S. A.; Dattelbaum, D. M.; Stahl, D. B.; Engelke, R.

2011-06-01

411

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

412

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

413

Detonation and incineration products of PBX explosives  

SciTech Connect

A series of experiments are planned to determine detonation product gases that are released into the environment when high explosives are tested. These experiments will be done in a 1.8-m-diam confinement vessel at ambient air pressure and partial vacuum. A matrix of four shots of PBX 9501, three shots of PBX 9502 and one shot of LX-10 are analyzed to determine the reproducibility and mass balance of materials in the detonation. This paper will only report on the detonation product gases as other experiments are planned.

Fletcher, M.A.; Loughran, E.D.

1992-01-01

414

Condensation of carbon during high explosive detonation  

NASA Astrophysics Data System (ADS)

The formation of nano-carbon clusters is believed to be responsible for the non-ideal detonation behavior of carbon-rich explosives, such as triamino-trinitrobenzene (TATB). We have developed a new model of carbon formation during detonation. The model is based on the assumption that carbon cluster growth has features of both activated Arrhenius kinetics and diffusion controlled kinetics. In our model the variation of temperature, density, and viscosity throughout the high explosive reaction zone and expansion is calculated using a thermochemical model linked to a hydrodynamic code. We compare our model to new experimental results on the size scaling of detonations in TATB-based explosives.

Fried, Laurence; Bastea, Sorin; Garza, Raul

2012-02-01

415

Deflagrations and Detonations in Thermonuclear Supernovae  

Microsoft Academic Search

We study a type Ia supernova explosion using three-dimensional numerical\\u000asimulations based on reactive fluid dynamics. We consider a delayed-detonation\\u000amodel that assumes a deflagration-to-detonation transition. In contrast to the\\u000apure deflagration model, the delayed-detonation model releases enough energy to\\u000aaccount for a healthy explosion, and does not leave carbon, oxygen, and\\u000aintermediate-mass elements in central parts of a white

Vadim N. Gamezo; Alexei M. Khokhlov; Elaine S. Oran

2004-01-01

416

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

417

DSD front models: nonideal explosive detonation in ANFO  

Microsoft Academic Search

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

John B. Bdzil; Tariq D. Aslam; Richard A. Catanach; L. G. Hill

2002-01-01

418

Experimental Investigations on Detonation Initiation in a Kerosene-Oxygen Pulse Detonation Rocket Engine  

Microsoft Academic Search

A series of experiments was carried out on a pulse detonation rocket engine (PDRE) running on a liquid kerosene-oxygen mixture to investigate the indirect detonation initiation. The experiments investigating the effect of Shchelkin spiral on the deflagration-to-detonation transition (DDT) process demonstrated that all spirals were able to enhance flame acceleration to some extent, but successful DDT was achieved only when

Jianling Li; Wei Fan; Chuanjun Yan; Qiang Li

2009-01-01

419

Experimental investigation on gaseous detonation propagation through a heart-shape tube  

NASA Astrophysics Data System (ADS)

Gaseous detonation of 2H2/O2/Ar mixture propagation through a heart-shape tube with a cross-section 50mm×40mm was experimentally studied in this paper. The pressure history at specific ports was recorded by pizeo-electric transducers and cellular patterns were obtained by smoked foils respectively. Results indicate that the CJ detonation can be obtained at the straight part of a heart-shape tube when detonator is used to ignite the combustible mixtures. The SDT process of detonator ignition is very complicated and its mechanism is different from that of DDT process of spark ignition. Detonation wave is strongly influenced by the geometry around the heart-shape of the tube. The cells along the concave wall are finer than those along the convex wall. The trajectory of triple point at the symmetrical section denotes the phenomena of very high pressure. Pressure histories show that transmitted shocks travel forward after two reversed leading shocks collide together.

Wang, C. J.; Xu, S. L.; Zhang, Y. J.

420

SLAG CHARACTERIZATION AND REMOVAL USING PULSE DETONATION TECHNOLOGY DURING COAL GASIFICATION  

SciTech Connect

Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. Conventional slag removal methods including soot blowers and water lances have great difficulties in removing slags especially from the down stream areas of utility power plant boilers. The detonation wave technique, based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. A slight increase in the boiler efficiency, due to more effective ash/deposit removal and corresponding reduction in plant maintenance downtime and increased heat transfer efficiency, will save millions of dollars in operational costs. Reductions in toxic emissions will also be accomplished due to reduction in coal usage. Detonation waves have been demonstrated experimentally to have exceptionally high shearing capability, important to the task of removing slag and fouling deposits. The experimental results describe the parametric study of the input parameters in removing the different types of slag and operating condition. The experimental results show that both the single and multi shot detonation waves have high potential in effectively removing slag deposit from boiler heat transfer surfaces. The results obtained are encouraging and satisfactory. A good indication has also been obtained from the agreement with the preliminary computational fluid dynamics analysis that the wave impacts are more effective in removing slag deposits from tube bundles rather than single tube. This report presents results obtained in effectively removing three different types of slag (economizer, reheater, and air-heater) t a distance of up to 20 cm from the exit of the detonation tube. The experimental results show that the softer slags can be removed more easily. Also closer the slag to the exit of the detonation tube, the better are their removals. Side facing slags are found to shear off without breaking. Wave strength and slag orientation also has different effects on the chipping off of the slag. One of the most important results from this study is the observation that the pressure of the waves plays a vital role in removing slag. The wave frequency is also important after a threshold pressure level is attained.

DR. DANIEL MEI; DR. JIANREN ZHOU; DR. PAUL O. BINEY; DR. ZIAUL HUQUE

1998-07-30

421

Overview of Pulse Detonation Propulsion Technology.  

National Technical Information Service (NTIS)

Propulsion systems based on the pulsed detonation cycle offer the potential to provide increased performance while simultaneously reducing engine weight, cost, and complexity, relative to conventional propulsion systems currently in service. The increased...

M. L. Coleman

2001-01-01

422

Cable discharge system for fundamental detonator studies.  

National Technical Information Service (NTIS)

Sandia National Laboratories has recently completed the modification and installation of a cable discharge system (CDS) which will be used to study the physics of exploding bridgewire (EBW) detonators and exploding foil initiators (EFI or slapper). Of pri...

G. R. Peevy S. G. Barnhart W. P. Brigham

1994-01-01

423

Computer modeling of electrical performance of detonators.  

National Technical Information Service (NTIS)

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...

C. M. Furnberg G. R. Peevy W. P. Brigham G. R. Lyons

1995-01-01

424

Parametric study of double cellular detonation structure  

NASA Astrophysics Data System (ADS)

A parametric numerical study is performed of a detonation cellular structure in a model gaseous explosive mixture whose decomposition occurs in two successive exothermic reaction steps with markedly different characteristic times. Kinetic and energetic parameters of both reactions are varied in a wide range in the case of one-dimensional steady and two-dimensional (2D) quasi-steady self-supported detonations. The range of governing parameters of both exothermic steps is defined where a "marked" double cellular structure exists. It is shown that the two-level cellular structure is completely governed by the kinetic parameters and the local overdrive ratio of the detonation front propagating inside large cells. Furthermore, since it is quite cumbersome to use detailed chemical kinetics in unsteady 2D case, the proposed work should help to identify the mixtures and the domain of their equivalence ratio where double detonation structure could be observed.

Khasainov, B.; Virot, F.; Presles, H.-N.; Desbordes, D.

2013-05-01

425

Explosion Phenomena Intermediate Between Deflagration and Detonation.  

National Technical Information Service (NTIS)

Explosives with stable propagation rates faster than those of conventional deflagrations and slower than those of conventional detonations should also produce intermediate pressures and action times, and could have numerous military and industrial uses. N...

J. A. Brown M. Collins

1967-01-01

426

Thermonuclear detonations and deflagrations in supernovae  

Microsoft Academic Search

Present understanding of supernova explosions is briefly reviewed. Thermonuclear deflagration and detonation models are compared in the light of observational evidence. Various diagnostic approaches to the explosion mechanism are considered.

J. C. Wheeler

1990-01-01

427

A C Firing Ability of Detonation.  

National Technical Information Service (NTIS)

This paper essentially analyses the series firing ability of detonators when subjected to AC mains voltage. The analysis and conclusions are made based on actual experiments conducted with the help of a custom built Electronic Firing system. At lower curr...

V. Arasu P. Satyavratan R. Vedam

1980-01-01

428

Detonation Cellular Structure and Image Processing.  

National Technical Information Service (NTIS)

Gaseous detonations universally exhibit an instability that is manifested as cellular patterns on witness plates (sooted foils) or open shutter photographs. The characteristic dimension or cell width lambda of the periodic cellular pattern has previously ...

J. E. Shepherd S. R. Tieszen

1986-01-01

429

CP DDT Detonators. I. Design Sensitivity Study.  

National Technical Information Service (NTIS)

A standard CP detonator design has been used to study a variety of design parameters including test temperature, closure disk thicknes, powder column diameter, transition column diameter, powder column confinement, igniter charge holder material, bridgewi...

J. W. Fronabarger M. L. Lieberman W. Fleming

1984-01-01

430

Detonative propagation and accelerative expansion of the Crab Nebula shock front.  

PubMed

The accelerative expansion of the Crab Nebula's outer envelope is a mystery in dynamics, as a conventional expanding blast wave decelerates when bumping into the surrounding interstellar medium. Here we show that the strong relativistic pulsar wind bumping into its surrounding nebula induces energy-generating processes and initiates a detonation wave that propagates outward to form the current outer edge, namely, the shock front, of the nebula. The resulting detonation wave, with a reactive downstream, then provides the needed power to maintain propagation of the shock front. Furthermore, relaxation of the curvature-induced reduction of the propagation velocity from the initial state of formation to the asymptotic, planar state of Chapman-Jouguet propagation explains the observed accelerative expansion. Potential richness in incorporating reactive fronts in the description of various astronomical phenomena is expected. PMID:22107499

Gao, Yang; Law, Chung K

2011-10-18

431

Inroad to modification of detonation nanodiamond  

Microsoft Academic Search

Our research is directed towards finding inroad(s) for conversion of detonation nanodiamond to more standard nanopowder with, first of all, enhancement of chemical and phase purity and, secondly, establish monofunctional surface termination. We have designed and tested a novel approach to detonation nanodiamond purification and surface functionalization, using a high temperature treatment in hydrogen-(H2, NH3) and chlorine-containing (Cl2, CCl4) gaseous

B. V. Spitsyn; J. L. Davidson; M. N. Gradoboev; T. B. Galushko; N. V. Serebryakova; T. A. Karpukhina; I. I. Kulakova; N. N. Melnik

2006-01-01

432

Hydraulic resistance and multiplicity of detonation regimes  

Microsoft Academic Search

The paper considers the effect of hydraulic resistance on detonation of gaseous premixtures. It is shown that the multiplicity of detonation regimes occasionally observed for explosions in rough tubes and in inert porous media may be successfully described in the framework of Zeldovich’s (1940) quasi-one-dimensional formulation, provided the class of admissible solutions is not restricted exclusively to the solutions involving

I. Brailovskya; G. Sivashinsky

2000-01-01

433

The Challenge of Non-Ideal Detonation  

Microsoft Academic Search

This paper will compare and contrast detonation in ideal and in highly non-ideal explosives. Ideal explosives, represented here by a TATB \\/ binder system, have relatively flat velocity of detonation (VoD) versus inverse charge diameter relationships, and fail at VoDs only slightly below their ideal CJ values. Highly non-ideal explosives, such as the physically heterogeneous composites used both in Naval

D. L. Kennedy

1995-01-01

434

Deflagration to detonation transition in thermonuclear supernovae  

SciTech Connect

The authors derive the criteria for deflagration to detonation transition (DDT) in a Type Ia supernova. The theory is based on the two major assumptions: (i) detonation is triggered via the Zeldovich gradient mechanism inside a region of mixed fuel and products, (ii) the mixed region is produced by a turbulent mixing of fuel and products either inside an active deflagration front or during the global expansion and subsequent contraction of an exploding white dwarf. The authors determine the critical size of the mixed region required to initiate a detonation in a degenerate carbon oxygen mixture. This critical length is much larger than the width of the reaction front of a Chapman-Jouguet detonation. However, at densities greater than = 5 x 10{sup 6} g/cc, it is much smaller than the size of a white dwarf. They derive the critical turbulent intensity required to create the mixed region inside an active deflagration front in which a detonation can form. They conclude that the density rho sub sigma at which a detonation can form in a carbon-oxygen white dwarf is low, approximately less than 2 to 5 x 10{sup 6} g/cc, but greater than 5 x 10{sup 6} g/cc.

Khokhlov, A.M.; Oran, E.S.; Wheeler, J.C.

1996-12-03

435

Application of Detonation Shock Dynamics (DSD) on Youngs-Type Discontinuous Interface Geometry  

NASA Astrophysics Data System (ADS)

Detonation Shock Dynamics (DSD) describes the evolution of two- or three-dimentional detonation wave by assuming that the detonation reaction zone is significantly small and that the curvature of the detonation wave front is also small with respect to the explosive in question. The current DSD solver obtains its input parameters by superimposing (normally rectangular Cartesian) grid points over the high explosive regions, determining signed distances from each grid point to the HE boundaries (+: inside of HE; -: outside) and assigning material identification to each grid point based on its location within the system. It has been shown to work with Lagrangian mesh where mesh entities, particularly cell faces, are contiguous and therefore, distances to material interfaces, namely HE and other materials and/or external boundaries, are precisely defined. In this paper a new scheme of DSD driver code to allow the material interfaces to be expressed in a discontinuous manner, such as Youngs material interface construction for 3D Eulerian hydrodynamics code.

Aida, Toru; Walter, John

2007-06-01

436

Influence of CF3H and CCl4 additives on acetylene detonation  

NASA Astrophysics Data System (ADS)

The influence of CF3 H and CCl4 admixtures (known as detonation suppressors for combustible mixtures) on the development of acetylene detonation was experimentally investigated in a shock tube. The time-resolved images of detonation wave development and propagation were registered using a high-speed streak camera. Shock wave velocity and pressure profiles were measured by five calibrated piezoelectric gauges and the formation of condensed particles was detected by laser light extinction. The induction time of detonation development was determined as the moment of a pressure rise at the end plate of the shock tube. It was shown that CF3H additive had no influence on the induction time. For CCl4, a significant promoting effect was observed. A simplified kinetic model was suggested and characteristic rates of diacetylene C4H2 formation were estimated as the limiting stage of acetylene polymerisation. An analysis of the obtained data indicated that the promoting species is atomic chlorine formed by CCl4 pyrolysis, which interacts with acetylene and produces C2H radical, initiating a chain mechanism of acetylene decomposition. The results of kinetic modelling agree well with the experimental data.

Drakon, A.; Emelianov, A.; Eremin, A.

2013-06-01

437

Computational Study of Near-Limit Propagation of Detonation in Hydrogen-Air Mixtures  

NASA Astrophysics Data System (ADS)

A computational investigation of the near-limit propagation of detonation in lean and rich hydrogen-air mixtures is presented. The calculations were carried out over an equivalence ratio range of 0.4 to 5.0, pressures ranging from 0.2 bar to 1.0 bar and ambient initial temperature. The computations involved solution of the one-dimensional Euler equations with detailed finite-rate chemistry. The numerical method is based on a second-order spatially accurate total-variation-diminishing (TVD) scheme, and a point implicit, first-order-accurate, time marching algorithm. The hydrogen-air combustion was modeled with a 9-species, 19-step reaction mechanism. A multi-level, dynamically adaptive grid was utilized in order to resolve the structure of the detonation. The results of the computations indicate that when hydrogen concentrations are reduced below certain levels, the detonation wave switches from a high-frequency, low amplitude oscillation mode to a low frequency mode exhibiting large fluctuations in the detonation wave speed; that is, a 'galloping' propagation mode is established.

Yungster, S.; Radhakrishnan, K.

2002-10-01

438

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

439

Investigation on Novel Methods to Increase Specific Thrust in Pulse Detonation Engines via Imploding Detonations  

Microsoft Academic Search

Pulse Detonation Engines (PDE) is seen to be the next generation propulsion systems due to enhanced thermodynamic efficiencies. One of the limitations in fielding practical designs has been attributed to tube diameters not exceeding 5 inches, thus affecting specific thrust. Novel methods via imploding detonations were investigated to remove such limitations. During the study, a practical computational cell size was

Ivan Ho

2009-01-01

440

Dynamic Behaviors of Lead Flyer Driven by Collision of Head-on Sliding Detonations  

NASA Astrophysics Data System (ADS)

The dynamic behaviors of lead plate driven by head-on sliding detonation waves were characterized with the help of high-speed frame photography and pulsed X-ray radiography. Experimental records have shown a jet like bulging in the collision region, size of which extended rapidly after the collision of the head-on detonation waves because of the obvious speed gradients of particles inside the bulging from the tip to the bottom of the bulging. Multi-layer like structure of loading front formed in the result of the impact of two symmetric detonation fronts. The mass densities inside the bulging structure fixed by the pulsed X-ray radiography were evaluated at the level of 1%˜10% from the initial density of lead. The dynamic strength and shock wave melting should have played dominate role in the formation of the initial stage and the evolution of cavitations and fragmentation process finished merely in microseconds inside the continuum of melted lead under the intensive tension of release wave, in the result of which a porous or dispersed stage bulging was formed.

Zhang, Chongyu; Hu, Haibo; Li, Qingzhong; Zhang, Zhengtao; Sun, Xuelin

2011-06-01

441

Realization and modeling of continuous spin detonation of a hydrogen-oxygen mixture in flow-type combustors. 2. Combustors with expansion of the annular channel  

Microsoft Academic Search

Results of a comprehensive numerical and experimental study of continuous spin detonation of an H2-O2 mixture in flow-type annular combustors with channel expansion are presented. In these experiments, oxygen is supplied as\\u000a a continuous flow through an annular slot, and hydrogen is injected through injectors. Combustion of hydrogen-oxygen mixtures\\u000a in continuously rotating (spinning) and pulsed detonation waves with exhaustion of

F. A. Bykovskii; S. A. Zhdan; E. F. Vedernikov

2009-01-01

442

Theoretical and computer models of detonation in solid explosives  

SciTech Connect

Recent experimental and theoretical advances in understanding energy transfer and chemical kinetics have led to improved models of detonation waves in solid explosives. The Nonequilibrium Zeldovich - von Neumann - Doring (NEZND) model is supported by picosecond laser experiments and molecular dynamics simulations of the multiphonon up-pumping and internal vibrational energy redistribution (IVR) processes by which the unreacted explosive molecules are excited to the transition state(s) preceding reaction behind the leading shock front(s). High temperature, high density transition state theory calculates the induction times measured by laser interferometric techniques. Exothermic chain reactions form product gases in highly excited vibrational states, which have been demonstrated to rapidly equilibrate via supercollisions. Embedded gauge and Fabry-Perot techniques measure the rates of reaction product expansion as thermal and chemical equilibrium is approached. Detonation reaction zone lengths in carbon-rich condensed phase explosives depend on the relatively slow formation of solid graphite or diamond. The Ignition and Growth reactive flow model based on pressure dependent reaction rates and Jones-Wilkins-Lee (JWL) equations of state has reproduced this nanosecond time resolved experimental data and thus has yielded accurate average reaction zone descriptions in one-, two- and three- dimensional hydrodynamic code calculations. The next generation reactive flow model requires improved equations of state and temperature dependent chemical kinetics. Such a model is being developed for the ALE3D hydrodynamic code, in which heat transfer and Arrhenius kinetics are intimately linked to the hydrodynamics.

Tarver, C.M.; Urtiew, P.A.

1997-10-01

443

Reduced yield detonation characteristics in large failure diameter materials  

SciTech Connect

We have made detailed measurements of the approach to steady, self-supported propagating shock waves at greatly reduced yield in composite propellants. Propa- gation velocities are less than one half the theoretical value expected for full reac- tion at the sonic plane. Previous experimental studies 1 have given evidence of similar behavior. Also, previous theoretical work 2 in an analytic form has shown the possibility of reduced yield detonations. We have developed a reaction model coupled with a hydrody- namic code that together provide a description of the coupling of the complex reac- tion behavior with shock propagation and expansion in energetic materials. The model results show clearly that if the dependence of reaction rate on pressure is of sufficiently low order and the mode of consumption is by "grain burning" the calcu- lated detonation behavior closely parallels the observed non-ideal results. We describe the experiments, the reaction model, and compare experimental and calculational results. We also extend the model to predict results in the unexplored regime of very large size charges.

Lambert, R R; Lee, E L; Maienschein, J L; Merill, C I; Nichols, III; Reaugh, J E

1998-08-10

444

Structure and properties of detonation soot particles  

SciTech Connect

The influence of TNT/RDX (50/50) detonation parameters and conservation conditions of detonation products during their expansion in hermetic detonation chamber on structure and phase composition of the detonation carbon has been considered. Systematic studies made it possible to establish the real structure of detonation carbon depending on experimental conditions. It has been shown that both during explosion in a chamber and thermal annealing in vacuum the nanoparticles of diamond have the tendency to transform not into graphite particles, as was assumed earlier, but into onionlike structures of fullerene series, composed of closed concentric carbon shells, the so-called carbon onions. The nanometer carbon particles have been obtained which comprise a diamond nucleus surrounded by a graphite-like mantle composed of quasi-spherical carbon shells which are the intermediate products of annealing of nanodiamond. The influence of initial sizes of the diamond particles and temperature on the annealing of diamond has been studied. {copyright} {ital 1996 American Institute of Physics.}

MalKOV, I.Y.; Titiov, V.M. [Lavrentyev Institute of Hydrodynamics, SD RAS, Novosibirsk, 630090 (Russia)

1996-05-01

445

Modeling of Non-Ideal Aluminized Detonations  

NASA Astrophysics Data System (ADS)

We have implemented a Wood-Kirkwood (WK) kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions, while other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. Within the context of WK theory, we study the chemical interaction between Al and HMX detonation products in non-ideal explosives. We develop a kinetic rate law for the burning of Al in condensed detonation that depends on the surface properties of the Al grains and the detonation product gases. Moreover, we use an exp-6 equation of state for the product fluids that reproduces a wide range experimental shock hugoniot and static compression data. We use a Murnaghan form for the equation of state of the solid and liquid Al and Al_2O_3. We find that we can replicate experimental detonation velocities to within a few per cent for a wide range of aluminum content. We discuss the uncertainties in our model and the implications of our results on the modeling of other non-ideal explosives. This work was performed under the auspices of the U. S. Department of Energy under Contract No. W-7405-ENG-48.

Howard, W. Michael; Fried, Laurence E.; Souers, P. Clark

1999-06-01

446

Pulsed Detonation Engines Manufactured from Materials Having Low Thermal Stability.  

National Technical Information Service (NTIS)

Pulsed detonation engines (PDEs), or various components thereof, such as the detonation chamber and/or nozzle, can be economically constructed from materials having low thermal stability, such as plastics, composites, and light metals. During operation, t...

D. Lianos S. Eidelman

2003-01-01

447

Future Modeling Needs in Pulse Detonation Rocket Engine Design.  

National Technical Information Service (NTIS)

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) Discussio...

B. Meade D. Talley D. Mueller D. Tew M. Guidos D. Seymour

2001-01-01

448

Equations of state for explosive detonation products: The PANDA model.  

National Technical Information Service (NTIS)

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 her...

G. I. Kerley

1994-01-01

449

Initiator Diffraction Limits for Pulse Detonation Engine Operation.  

National Technical Information Service (NTIS)

Operational characteristics of a valveless pulse detonation engine system are being characterized by both experimental and computational efforts. The detonation diffraction process from a small 'initiator' combustor to a larger diameter main combustor in ...

S. P. Werner

2002-01-01

450

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Compatibility of electric detonators. 57.6400 Section...AND NONMETAL MINES Explosives Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All electric...

2013-07-01

451

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2013 CFR

...explosives and detonators are transported by any cars or vehiclesâ (1) The cars or vehicles shall be marked with warnings to...detonators shall be transported either in separate cars or vehicles, or if in the same cars or...

2013-07-01

452

Experimental study of a pulse detonation rocket with Shchelkin spiral  

Microsoft Academic Search

Aerodynamics Research Center, University of Texas at Arlington, TX 76019, USA There is much recent interest in the development of propulsion systems using high-frequency pulsed detonations [1]. An important technical challenge remains the ability to achieve consistent, repetitive detonations in a short distance. The direct initiation of detonation requires an inordinate amount of energy while a deflagration-to-detonation transition (DDT) occurs

F. K. Lu; J. M. Meyers; D. R. Wilson

2005-01-01

453

Experimental study of a pulse detonation rocket with Shchelkin spiral  

NASA Astrophysics Data System (ADS)

Aerodynamics Research Center, University of Texas at Arlington, TX 76019, USA There is much recent interest in the development of propulsion systems using high-frequency pulsed detonations [1]. An important technical challenge remains the ability to achieve consistent, repetitive detonations in a short distance. The direct initiation of detonation requires an inordinate amount of energy while a deflagration-to-detonation transition (DDT) occurs at lower energies but requires excessive length for aerospace propulsion applications.

Lu, F. K.; Meyers, J. M.; Wilson, D. R.

454

Mechanisms for Detonation Initiation in Type Ia Supernovae  

Microsoft Academic Search

We consider possible mechanisms for detonation initiation in an exploding carbon-oxygen white dwarf. According to current models of Type Ia supernovae, the explosion starts as a thermonuclear deflagration, but ends as a detonation. The process of deflagration-to-detonation transition (DDT) is still not well understood, though there are several scenarios that may lead to the detonation initiation. These include mixing between

Vadim N. Gamezo; E. S. Oran

2008-01-01

455

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

456

Quantic Industries Inc. slapper detonator performance  

SciTech Connect

Under the Lawrence Livermore National Laboratories (LLNL) Small Business Technology Transfer Program, assistance was given to Quantic Industries Inc. to use the High Explosive Applications Facility (HEAF), its apparatus, and LLNL expertise to characterize the performance of Quantic`s micro-clad copper/kapton slapper detonator assemblies and establish their threshold to detonate HNS-IV. The project involved measuring the performance of these slapper detonators, otherwise known as Exploding Foil Initiators (EFI`s), manufactured by Quantic Industries Inc. Slapper performance was measured by using a laser velocimeter, which is an expensive and specialized facility which Quantic does not own. The authors measured slapper velocity vs. time as a function of charging voltage. Quantic supplied slappers which were coated with {approximately}100 nm of Al to provide a reflective surface for the laser velocimeter measurements. LLNL provided to a capacitor discharge unit (CDU) to fire the slappers and matched the Quantic CDU waveforms as close as possible.

Cutting, J.L.; Lee, R.S.; Hodgin, R.L.

1994-05-01

457

Freesurface velocity measurements of plates driven by reacting and detonating RX03BB and PBX0404  

Microsoft Academic Search

Copper plates 90 mm in diameter, of thickness 0.25 mm and 0.5 mm, were accelerated by an adjacent 17 mm thick cylinder of RX-03-BB or PBX-9404-03. The explosive was initiated by impact of a thick flyer from the LLNL 102 mm gun, providing either a reactive or fully detonating wave, by appropriate choice of flyer velocities up to 1.30 mm\\/..mu..s.

L. M. Erickson; H. G. Palmer; N. L. Parker; H. C. Vantine

1981-01-01

458

Freesurface velocity measurements of plates driven by reacting and detonating RX03BB and PBX9404  

Microsoft Academic Search

Copper plates 80 mm in diameter, of thickness 0.25 mm and 0.5 mm, were accelerated by adjacent 17 mm thick, 90 mm diameter cylinders of RX-03-BB or PBX-9404-03. The explosive was initiated by impact of a thick flyer from the LLNL 102 mm gun, providing either a reactive or fully detonating wave, by approprite choice of flyer velocities up to

L. M. Erickson; H. G. Palmer; N. L. Parker; H. C. Vantine

1982-01-01

459

Role of chemical kinetics on the detonation properties of hydrogen \\/natural gas\\/air mixtures  

Microsoft Academic Search

The first part of the present work is to validate a detailed kinetic mechanism for the oxidation of hydrogen–methane–air mixtures in detonation waves. A series of experiments on auto-ignition delay times have been performed by shock tube technique coupled with emission spectrometry for H2\\/CH4\\/O2 mixtures highly diluted in argon. The CH4\\/H2 ratio was varied from 0 to 4 and the

N. Chaumeix; S. Pichon; F. Lafosse; C.-E. Paillard

2007-01-01

460

Numerical simulation of detonation initiation in a flame brush: the role of hot spots  

Microsoft Academic Search

This is the final paper in a series describing numerical simulations of deflagration-to-detonation transition (DDT) for conditions similar to reflected shock-tube experiments in an acetylene–air mixture (100 Torr, 298 K). In the experiments and calculations, the interaction of a shock wave and an expanding flame front leads to the rapid creation of a turbulent flame brush and, for sufficiently high

Alexei M. Khokhlov; Elaine S. Oran

1999-01-01