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1

Effect of laser supported detonation wave confinement on termination conditions  

NASA Astrophysics Data System (ADS)

A laser supported detonation (LSD) wave was driven using line-focusing laser optics, in which an induced blast wave expanded laterally from the LSD region to surrounding air in two-dimensional space. The LSD wave was confined in quasi-1D space using a wedge nozzle to restrict the lateral expansion of a blast wave. The LSD termination threshold and the blast wave energy were deduced from shadowgraphs showing the blast wave expansion. The respective threshold laser intensities for cases with and without confinement were estimated as 17 and 34 GW/m2, indicating that the lateral expansion strongly influenced on the LSD termination condition.

Ushio, Masato; Komurasaki, Kimiya; Kawamura, Koichi; Arakawa, Yoshihiro

2008-06-01

2

Structure and maintenance threshold of laser supported detonation waves  

NASA Astrophysics Data System (ADS)

Maintenance of a Chapman Jouguet laser supported detonation (LSD) wave requires complete absorption of the laser beam in an absorption front travelling supersonically with respect to the upstream gas. A requirement for LSD maintenance is that this distance be less than the radius of the beam. A computational scheme was developed to study the structure of LSD waves in various gases. A simultaneous solution of the mass and momentum conservation equations yields a (Maxwell) line when p is plotted versus 1/?, the slope of which is related to the velocity of the wave. The physical distance x in the wave corresponding to each point on the Maxwell line is determined by calculating the inverse bremsstrahlung absorption coefficient k as a function of the p and ? and then inverting the equation Iabs (p, ?)=Io (1-exp-?x k dx') for x. The method is used to calculate wave thicknesses for a variety of gases (H2O, LiH) that are being considered as propellant materials for laser propulsion. Results are presented for a laser wavelength of 10.6 ?m and upstream gas densities in the 10-3 to 10-4 g/cc range. The effect of adding a low ionization potential seed to the propellant is explicitly calculated.

Weyl, G.; Rollins, C.; Resendes, D.

1990-07-01

3

Lateral expansion of a laser-supported detonation wave in a gas.  

NASA Technical Reports Server (NTRS)

A model satisfying the conditions in the burnt (ionized) and ambient undisturbed gases is presented for the two-dimensional case of the absorption wave resulting from the interaction of a laser beam with the plasma it generates in the gas through which the beam propagates. The flowfield of the rarefaction wave resulting from the laser-supported detonation is discussed, along with the computed shock and flow deflection angles.

Howe, J. T.

1972-01-01

4

Fundamental Properties of Non-equilibrium Laser-Supported Detonation Wave  

SciTech Connect

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

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

2004-03-30

5

Numerical Analysis of Effects of Incident Laser Wavelength on Thermal Nonequilibrium Laser-supported Detonation Wave  

NASA Astrophysics Data System (ADS)

Laser-supported detonation (LSD) waves are important because they can generate the high pressures and high temperatures necessary for laser propulsion systems. Although CO2 laser beams, which have a wavelength of 10.6 ?m, have been considered to be one of the most powerful sources of LSD waves, a glass laser beam (1.053?m), for example, also have high power. In this study, we numerically simulated LSD waves propagating through a diatomic gas, in order to evaluate the effects of incident laser wavelength on the construction of the LSD wave. We used the physical-fluid dynamics scheme, which has been developed for simulating unsteady and nonequilibrium LSD waves propagating through hydrogen gas.

Shiraishi, Hiroyuki; Koide, Takuya; Nakamori, Manabu

6

Energy Conversion Process in Laser Supported Detonation Waves Induced by a Line-Focusing Laser  

NASA Astrophysics Data System (ADS)

Propagation of two-dimensional and quasi-one-dimensional Laser Supported Detonation (LSD) waves driven by a line-focusing laser beam was investigated using the shadowgraph method. As a result, fractional laser absorption during the LSD regime for 2D and quasi-1D cases was 68% and 81%, respectively, which was lower than that of three-dimensional LSD wave driven by a point-focusing beam (typically 90%.) However, the blast wave energy efficiency was found proportional to the fractional absorption. Besides, the LSD threshold intensity was apparently lowered in the quasi-1D case due to the momentum confinement effect. Comparison with the quasi-1D simulation considering the real gas effects suggests that non-equilibrium effects and radiation loss should be playing an important role in the energy conversion process in the LSD regime.

Ushio, Masato; Kawamura, Koichi; Komurasaki, Kimiya; Katsurayama, Hiroshi; Koizumi, Hiroyuki; Arakawa, Yoshihiro

2006-05-01

7

Implications of applying a global energy balance to laser-supported and chemical detonation waves  

Microsoft Academic Search

A closer examination of the conditions needed to propagate a steady-state shock wave is made and generalized to include energy added in the vicinity of the wave via both laser deposition and chemical rections. This analysis yields slightly different results than standard detonation theory, and these differences are explored. A case is made for the correctness of the present method

E. J. Jumper

1984-01-01

8

Implications of applying a global energy balance to laser-supported and chemical detonation waves  

NASA Astrophysics Data System (ADS)

A closer examination of the conditions needed to propagate a steady-state shock wave is made and generalized to include energy added in the vicinity of the wave via both laser deposition and chemical rections. This analysis yields slightly different results than standard detonation theory, and these differences are explored. A case is made for the correctness of the present method by citing the results of other researchers.

Jumper, E. J.

1984-09-01

9

Numerical Analysis of Threshold between Laser-Supported Detonation and Combustion Wave Using Thermal Non-Equilibrium and Multi-Charged Ionization Model  

NASA Astrophysics Data System (ADS)

Laser-supported Detonation (LSD), which is one type of Laser-supported Plasma (LSP), is an important phenomenon because it can generate high pressures and temperatures for laser absorption. In this study, using thermal-non-equilibrium model, we numerically simulate LSPs, which are categorized as either LSDs or laser-supported combustion-waves (LSCs). For the analysis model, a two-temperature (heavy particle and electron-temperature) model has been used because the electronic mode excites first in laser absorption and a thermal non-equilibrium state easily arises. In the numerical analysis of the LSDs, laser absorption models are particularly important. Therefore, a multi-charged ionization model is considered to evaluate precisely the propagation and the structure transition of the LSD waves in the proximity of the LSC-LSD threshold. In the new model, the transition of the LSD construction near the threshold, which is indicated by the ionization delay length, becomes more practical.

Shiraishi, Hiroyuki; Kumagai, Yuya

10

Laser Wavelength Dependency of Laser Supported Detonation  

NASA Astrophysics Data System (ADS)

The development of high power Neodymium glass (Nd:glass) laser allows for application in laser propulsion. The Nd:glass laser is one of a candidate of the driver for the propulsion. However, there is a lack of study with using the solid state laser. Previous studies found that plasma induced using the glass laser absorbs the laser energy during a short laser supported detonation (LSD) regime compared with CO2 lasers. To investigate a laser wavelengths dependency of LSD in comparison with the CO2 laser, we used plasma emission spectroscopy and measured the electron temperature and electron density. As a result, these parameters of the glass laser appear to be higher value than those for the CO2 laser plasma. Besides, the absorption depth behind the shock wave is longer than that one of the CO2 laser. The results reveal that the long depth absorbs the energy conversion efficiency at almost same order despite a short LSD duration, as compared with the CO2 laser.

Shimamura, Kohei; Michigami, Keisuke; Wang, Bin; Yamaguchi, Toshikazu; Komurasaki, Kimiya; Arakawa, Yoshihiro

2011-11-01

11

Influence of the gaseous form on the precursor heating layer of a laser-supported detonation wave using half self-emission half shadowgraph visualization  

NASA Astrophysics Data System (ADS)

After breakdown one of the possible mechanisms of occurrence of laser-produced plasma is noted as laser-supported detonation (LSD) wave. This wave consisting of the shock wave and the beam absorbing plasma travels at 1-10 km/s along the beam channel in the direction opposite to the laser incidence. The laser heating structure is recognized as the ZND model of chemical detonation. However, Shimamura et. al, showed that the plasma proceeds the shock wave during LSD regime. The role of shock compression is relatively smaller than preheating by laser. The conventional model is inconsistent with our paper. To investigate the heating structure of a LSD wave, half self-emission half shadowgraph (HSHS) methods provides the self-emission image from the plasma on the top half and the shadowgraph image of the induced shock wave on the bottom half simultaneously. A TEA CO2 laser was used at 10 J incident energy. The locations of both wave fronts were detected from the brightness distribution of the HSHS images. As a result, the propagation of ionization front precedes that of shock wave front by the order of 10-4 m in air and N2. Preheating layer of N2 is shorter than that of air because O2 in air has the lowest ionization energy. Thus, a characteristic of preionization layer depends on the ionization properties because photoionization by the UV radiation generate the seed electrons ahead of shock wave.

Shimamura, Kohei; Michigami, Keisuke; Ofoso, Joseph; Komursaki, Kimiya

2012-10-01

12

Terminating Conditions of Laser Supported Detonation in Two Different Lasers  

NASA Astrophysics Data System (ADS)

Laser Supported Detonation (LSD) wave is the major efficient energy conversion structure in Repetitively Pulsed Laser Propulsion, which is known as one of the promising candidates for future space launching system. In order to advance the launching performance, it is quite important to find out the terminating condition of LSD. It is known that feature of high power lasers is one of the crucial factors for LSD wave. Former studies were concentrated on the LSD wave generated by CO2 laser, however, the structure of LSD induced by solid laser haven't been well investigated yet. In this paper, by applying the visual technique of Schlieren, images of LSD wave generated by Nd:Glass laser were obtained around its ending time. After which, a compare of the LSD termination condition between the using of CO2 laser and Glass laser were given from experimental aspects.

Yamaguchi, Toshikazu; Wang, Bin; Shimada, Yutaka; Shimamura, Kohei; Hatai, Keigo; Komurasaki, Kimiya; Arakawa, Yoshihiro

2010-05-01

13

INVESTIGATION OF LASER SUPPORTED DETONATION WAVES AND THERMAL COUPLING USING 2.8um HF LASER IRRADIATED METAL TARGETS  

E-print Network

(LSD) waves and thermal cou- pling for HF laser irradiated solid targets have been investigated as a function of target material, irradiance and ambient pressure. High speed photography has been employed to study the plasma dyna- mics and the thresholds for plasmotron and LSD wave production obtained

Boyer, Edmond

14

Understanding curved detonation waves  

SciTech Connect

A wave curve is the set of final states to which an initial state may be connected by a traveling wave. In gas dynamics, for example, the wave curve consists of the shock Hugoniot curve for compressive waves and the rarefaction curve for expansive waves. In this paper, we discuss the wave curve for an undriven planar detonation and for general planar detonations. We then extend the wave curve concept to detonations in converging and diverging geometry. We also discuss the application of these wave curves to the numerical computation of detonation problems.

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

1992-10-01

15

Understanding curved detonation waves  

SciTech Connect

A wave curve is the set of final states to which an initial state may be connected by a traveling wave. In gas dynamics, for example, the wave curve consists of the shock Hugoniot curve for compressive waves and the rarefaction curve for expansive waves. In this paper, we discuss the wave curve for an undriven planar detonation and for general planar detonations. We then extend the wave curve concept to detonations in converging and diverging geometry. We also discuss the application of these wave curves to the numerical computation of detonation problems.

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

1992-01-01

16

Oblique detonation wave ramjet  

NASA Technical Reports Server (NTRS)

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

Morrison, R. B.

1980-01-01

17

THE STRUCTURE OF DETONATION WAVES  

Microsoft Academic Search

Multidimensional time-dependent numerical simulations have been used to study the initi- ation, propagation, and extinction of detonations in gases and liquids. The simulations, which calculate the detailed behavior of the interacting shock waves and reaction zones forming the detonation wave, are used to study the evolution of the instability that leads to the cellular structure of detonations. The simulations consist

E. S. ORAN; K. KAILASANATH; R. H. GUIRGUIS

1987-01-01

18

Photoionization in the Precursor of Laser Supported Detonation by Ultraviolet Radiation  

SciTech Connect

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

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

2011-11-10

19

Photoionization in the Precursor of Laser Supported Detonation by Ultraviolet Radiation  

NASA Astrophysics Data System (ADS)

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 ?s and 0.3 ?s, resp. Besides, argon plasma emitted 1010 to 1014 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; Arakawa, Yoshihiro

2011-11-01

20

A reexamination of the laser supported combustion wave  

NASA Technical Reports Server (NTRS)

Kantrowitz (1972) and Minovitch (1972) have proposed the use of laser sustained plasmas as a means to heat a rocket propellant. Recent studies of laser-powered propulsion have been directed toward the application of high-specific-impulse space propulsion systems for orbital transfer missions. Analyses of rocket performance relied heavily on the concept of the laser-supported combustion (LSC) wave. Raizer (1971) first drew the analogy between laser-sustained plasmas and combustion waves in an analysis. The Raizer model was later applied to hydrogen by Kemp and Root (1979). In connection with certain problems arising with the approach considered by Kemp and Root, the present investigation is concerned with a reexamination of the Raizer model. Attention is given to a numerical approach for the entire LSC wave in hydrogen, taking into account the incorporation of the proper boundary conditions far downstream of the wave.

Keefer, D.; Peters, C.; Crowder, H.

1983-01-01

21

Detonation Wave Propagation in an Ejector-Augmented Pulse Detonation Rocket  

E-print Network

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

Texas at Arlington, University of

22

Evaluation of the oblique detonation wave ramjet  

NASA Technical Reports Server (NTRS)

The potential performance of oblique detonation wave ramjets is analyzed in terms of multishock diffusion, oblique detonation waves, and heat release. Results are presented in terms of thrust coefficients and specific impulses for a range of flight Mach numbers of 6 to 16.

Morrison, R. B.

1978-01-01

23

Detonation wave augmentation of gas turbines  

NASA Technical Reports Server (NTRS)

The results of a feasibility study that examined the effects of using detonation waves to augment the performance of gas turbines are reported. The central ideas were to reduce compressor requirements and to maintain high performance in jet engines. Gasdynamic equations were used to model the flows associated with shock waves generated by the detonation of fuel in detonator tubes. Shock wave attenuation to the level of Mach waves was found possible, thus eliminating interference with the compressor and the necessity of valves and seals. A preliminary parametric study of the performance of a compressor working at a 4:1 ratio in a conceptual design of a detonation wave augmented jet engine in subsonic flight indicated a clear superiority over conventional designs in terms of fuel efficiency and thrust.

Wortman, A.

1984-01-01

24

Detonation wave compression in gas turbines  

NASA Technical Reports Server (NTRS)

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

Wortman, A.

1986-01-01

25

Interaction of turbulence with a detonation wave  

NASA Technical Reports Server (NTRS)

This paper addresses a specific reactive-flow configuration, namely, the interaction of a detonation wave with convected homogeneous isotropic weak turbulence (which can be constructed by a Fourier synthesis of small-amplitude vorticity waves). The effect of chemical heat release on the rms fluctuations downstream of the detonation is presented as a function of Mach number. In addition, for the particular case of the von Karman spectrum, the one-dimensional power spectra of these flow quantities are given.

Jackson, T. L.; Hussaini, M. Y.; Ribner, H. S.

1993-01-01

26

High order hybrid numerical simulations of two dimensional detonation waves  

NASA Technical Reports Server (NTRS)

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

Cai, Wei

1993-01-01

27

On the Existence of Pathological Detonation Waves  

NASA Astrophysics Data System (ADS)

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

Tarver, Craig M.

2004-07-01

28

Analytical study of laser supported combustion waves in hydrogen  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

29

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

30

Numerical modelling of shock waves and detonation in complex geometries  

E-print Network

Cumulation of shock snd detonation waves was considered. Computations were carried out by use of second-order central-difference scheme. Cumulation of waves in cone region with scales of 1 meter was studied. Pictures of flow in shock and detonation waves during different time moments were obtained as well as time dependences and maximum pressures for different corner angles.

Nevmerzhitskiy, Y V

2012-01-01

31

A Fully Conservative Ghost Fluid Method & Stiff Detonation Waves  

Microsoft Academic Search

We present a new, fully conservative version of the ghost fluid method applicable for tracking material interfaces, inert shocks, and both deflagration and detonation waves in as many as three spatial dimensions. The exact discrete conservation properties are most important when tracking inert shocks and detonation waves, so that is the focus of this paper. In particular, we address the

Duc Nguyen; Frédéric Gibou; Ronald Fedkiw

2002-01-01

32

Detonation wave velocity and curvature of brass encased PBXN-111  

SciTech Connect

Detonation velocities and wave front curvatures were measured for PBXN-111 charges encased in 5 mm thick brass tubes. In all the experiments (charge diameters from 19 to 47 mm) the brass case affected the detonation properties of PBXN-111. Steady detonation waves propagated in brass encased charges with diameters as small as 19 mm, which is about half of the unconfined failure diameter. The radii of curvature of the detonation waves at the center of the wave fronts ranged from 52 to 141 mm for charge diameters of 25 to 47 mm. The angles between the detonation wave fronts and the brass/charge interfaces were between 72 and 74 degrees. {copyright} {ital 1996 American Institute of Physics.}

Forbes, J.W.; Lemar, E.R. [Naval Surface Warfare Center, Indian Head Division, Silver Spring, Maryland 20903-5640 (United States)

1996-05-01

33

Detonation wave phenomena in bubbled liquid  

NASA Astrophysics Data System (ADS)

Shock wave propagation was investigated in two phase media consisting of diluted glycerin (85%) and reactive gas bubbles. To understand these complex phenomena, we first performed a numerical analysis and experimental studies of single bubbles containing a reactive gas-mixture. For the two-phase mixtures, a needle matrix bubble-generator enabled us to produce a homogeneous bubble distribution with a size dispersion less than 5%. The void fraction ?0 was varied over one order of magnitude, ?0=0.2-2%. It was found that there exists a critical value of shock strength above which bubble explosion starts. Once a bubble explodes, it stimulates the adjacent bubbles to explode due to emission of a blast wave; this process is followed by a series of similar events. A steady detonationlike wave propagates as a precurser with a constant velocity which is much higher than that of the first wave. To study the structure of the detonation wave the measured pressured profiles were averaged by superimposing 50 shots.

Gülhan, A.; Beylich, A. E.

1990-07-01

34

Low Velocity Detonation of Nitromethane Affected by Precursor Shock Waves Propagating in Various Container Materials  

Microsoft Academic Search

It is well known that some liquid explosives have two detonation behaviors, high velocity detonation (HVD) or low velocity detonation (LVD) can propagate. A physical model to describe the propagation mechanism of LVD in liquid explosives was proposed that LVD is not a self-reactive detonation, but rather a supported-reactive detonation from the cavitation field generated by precursor shock waves. However,

Hideki Hamashima; Akinori Osada; Yukio Kato; Shigeru Itoh

2007-01-01

35

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

36

Simulation of cellular structure in a detonation wave  

Microsoft Academic Search

The cell structure of a detonation wave in a hydrogen-oxygen-argon mixture is studied computationally using a two-dimensional, time-dependent solution of the compressible reactive-flow equations. A phenomenological model is used to represent the conversion of reactants to products and energy release. The particular case studied here resolves the structure and dynamics of one detonation cell in great detail. The computations show

M. H. Lefebvre; E. S. Oran; K. Kailasanath; P. J. van Tiggelen

1993-01-01

37

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

38

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

39

Experimental Study on Transmission of an Overdriven Detonation Wave Across a Mixture  

E-print Network

Experimental Study on Transmission of an Overdriven Detonation Wave Across a Mixture J. Li1 , K a strong overdriven state in a weaker mixture by propagating an overdriven detonation wave via/oxygen mixture were used to evaluate the attenuation of the overdriven detonation wave in the DDT process. Next

Texas at Arlington, University of

40

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

41

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

42

Detonation wave phenomena in bubbled liquid  

Microsoft Academic Search

Shock wave propagation was investigated in two phase media consisting of diluted glycerin (85%) and reactive gas bubbles. To understand these complex phenomena, we first performed a numerical analysis and experimental studies of single bubbles containing a reactive gas-mixture. For the two-phase mixtures, a needle matrix bubble-generator enabled us to produce a homogeneous bubble distribution with a size dispersion less

A. E. Beylich

1990-01-01

43

Detonation wave phenomena in bubbled liquid  

Microsoft Academic Search

Shock wave propagation was investigated in two phase media consisting of diluted glycerin (85%) and reactive gas bubbles. To understand these complex phenomena, we first performed a numerical analysis and experimental studies of single bubbles containing a reactive gas-mixture. For the two-phase mixtures, a needle matrix bubble-generator enabled us to produce a homogeneous bubble distribution with a size dispersion less

A. Gülhan; A. E. Beylich

1990-01-01

44

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

45

Temperature Measurements of Shock Waves and Detonations by Spectrum-line Reversal. IV. Development of Detonations  

Microsoft Academic Search

The temperature distribution behind shock fronts and detonations through mixtures of oxygen with hydrogen, methane, methanol, ethylene and carbon monoxide has been studied by the method of spectrum-line reversal; simultaneously, measurements were made of pressure and shock speed. The spectrum and time history of the light emitted by the detonating gases were also examined. The detonations were initiated by shock

A. G. Gaydon; I. R. Hurle; G. H. Kimbell

1963-01-01

46

A Fully Conservative Ghost Fluid Method & Stiff Detonation Waves Computer Science Department  

E-print Network

A Fully Conservative Ghost Fluid Method & Stiff Detonation Waves Duc Nguyen Computer Science University Stanford, CA 94305 We present a new, fully conservative version of the ghost fluid method the level set method to track the location of the detonation wave and the ghost fluid method to treat

Fedkiw, Ron

47

Micro-blast waves using detonation transmission tubing  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

48

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

49

Application of detonation wave theory to subcritical vapor explosions  

SciTech Connect

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

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

1995-07-01

50

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

51

Nonlinear interaction of a detonation/vorticity wave  

NASA Technical Reports Server (NTRS)

The interaction of an oblique, over driven detonation wave with a vorticity disturbance is investigated by a direct two-dimensional numerical simulation using a multi-domain, finite-difference solution of the compressible Euler equations. The results are compared to those of linear theory, which predict that the effect of exothermicity on the interaction is relatively small except possibly near a critical angle where linear theory no longer holds. It is found that the steady-state computational results agree with the results of linear theory. However, for cases with incident angle near the critical angle, moderate disturbance amplitudes, and/or sudden transient encounter with a disturbance, the effects of exothermicity are more pronounced than predicted by linear theory. Finally, it is found that linear theory correctly determines the critical angle.

Lasseigne, D. G.; Jackson, T. L.; Hussaini, M. Y.

1991-01-01

52

Non-linear interaction of a detonation/vorticity wave  

NASA Technical Reports Server (NTRS)

The interaction of an oblique, overdriven detonation wave with a vorticity disturbance is investigated by a direct two-dimensional numerical simulation using a multi-domain, finite-difference solution of the compressible Euler equations. The results are compared to those of linear theory, which predict that the effect of exothermicity on the interaction is relatively small except possibly near a critical angle where linear theory no longer holds. It is found that the steady-state computational results agree with the results of linear theory. However, for cases with incident angle near the critical angle, moderate disturbance amplitudes, and/or sudden transient encounter with a disturbance, the effects of exothermicity are more pronounced than predicted by linear theory. Finally, it is found that linear theory correctly determines the critical angle.

Lasseigne, D. G.; Jackson, T. L.; Hussaini, M. Y.

1991-01-01

53

Temperature measurement in spherically conveying detonation waves. Experimental results with an 800 mm apparatus  

Microsoft Academic Search

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 intensity of Ar lines was determined as a function of time. The measured peak temperature behind the detonation front shows the same radial

Kunio Terao

1985-01-01

54

Head-on Collision of a Detonation with a Planar Shock Wave  

NASA Astrophysics Data System (ADS)

The phenomenon that occurs when a Chapman Jouguet (CJ) detonation collides with a shock wave is discussed. Assuming a one-dimensional steady wave configuration analogous to a planar shock shock frontal interaction, analytical solutions of the Rankine Hugoniot relationships for the transmitted detonation and the transmitted shock are obtained by matching the pressure and particle velocity at the contact surface. The analytical results indicate that there exist three possible regions of solutions, i.e. the transmitted detonation can have either strong, weak or CJ solution, depending on the incident detonation and shock strengths. On the other hand, if we impose the transmitted detonation to have a CJ solution followed by a rarefaction fan, the boundary conditions are also satisfied at the contact surface. The existence of these multiple solutions is verified by an experimental investigation. It is found that the experimental results agree well with those predicted by the second wave interaction model and that the transmitted detonation is a CJ detonation. Unsteady numerical simulations of the reactive Euler equations with both simple one-step Arrhenius kinetic and chain-branching kinetic models are also carried out to look at the transient phenomena and at the influence of a finite reaction thickness of a detonation wave on the problem of head-on collision with a shock. From all the computational results, a relaxation process consisting of a quasi-steady period and an overshoot for the transmitted detonation subsequent to the head-on collisions can be observed, followed by the asymptotic decay to a CJ detonation as predicted theoretically. For unstable pulsating detonations, it is found that, due to the increase in the thermodynamic state of the reactive mixture caused by the shock, the transmitted pulsating detonation can become more stable with smaller amplitude and period oscillation. These observations are in good agreement with experimental evidence obtained from smoked foils where there is a significant decrease in the detonation cell size after a region of relaxation when the detonation collides head-on with a shock wave.

Ng, H. D.; Botros, B. B.; Chao, J.; Yang, J. M.; Nikiforakis, N.; Lee, J. H. S.

2006-09-01

55

Study of Detonation Wave Structure in Solid and Liquid Tetranitromethane (TNM)  

NASA Astrophysics Data System (ADS)

Investigations of detonation front structure and parameters in solid and liquid tetranitromethane were done using Doppler Fabry-Perot velocimeter. We recorded the particle velocity of explosion products, braking on the HE/window interface. Smooth front of the detonation wave and concave negative-going particle velocity profile were recorded for liquid TNM. The experimental records indicate that because of solid TNM heterogeneity flow, turbulization occurs behind detonation wave front what appears in the form of velocity fluctuations on the U(t) profile.

Fedorov, A. V.; Mikhailov, A. L.; Nazarov, D. V.; Finyushin, S. A.; Men'shikh, A. V.; Davydov, V. A.; Govorunova, T. A.

2006-07-01

56

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

SciTech Connect

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

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

2013-01-28

57

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

NASA Astrophysics Data System (ADS)

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

Huifeng, Tong; Zhiping, Tang

2011-06-01

58

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

NASA Astrophysics Data System (ADS)

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

Tong, Huifeng; Yuan, Hong; Tang, Zhiping

2013-01-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

60

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

61

Ignition of Flamelets Behind Incident Shock Waves and the Transition to Detonation  

Microsoft Academic Search

Time-dependent numerical simulations are used to elucidate some of the details of weak ignition behind incident shocks and the subsequent transition to detonation. It is shown that a small amount of energy released in the shocked region can be the origin of pressure waves which accelerate the shock front. The simulations presented here show how this leads to the formation

K. Kailasanath; E. S. Oran

1983-01-01

62

Dynamics of detonation waves in a channel with variable cross section and filled with bubbly fluid  

NASA Astrophysics Data System (ADS)

The flow of bubbly fluid comprising a mixture of bubbles filled with explosive and inert gases, which is driven through a converging channel, was studied. Depending on the velocity of the hummer hitting the bubbly fluid boundary, the flow may be accompanied by the development of detonation waves which compress the bubbles with inert gas.

Topolnikov, A. S.; Gimaltdinov, I. K.

2014-08-01

63

The effect of freestream variations on the propagation of detonation and combustion waves  

E-print Network

NOMENCLATURE Et El E2 local speed of sound speed of detonation wave total energy activation energy for induction varable a activation energy for reaction variable P reaction rate for induction time K2, K3 reaction rates for exothermic reaction Lg... order diffusion speed of gas spatial coordinate position of outer shock wave progress parameter for induction time progress parameter for exothermic reaction ratio of specific heats limited flux value damping factor for Flux Corrected Transport...

Clark, Marlon Lee

2012-06-07

64

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

65

Geometric Scaling for a Detonation Wave Governed by a Pressure-Dependent Reaction Rate and Yielding Confinement  

E-print Network

The propagation of detonation waves in reactive media bounded by an inert, compressible layer is examined via computational simulations in two different geometries, axisymmetric cylinders and two dimensional, planar slabs. For simplicity, an ideal gas equation of state is used with a pressure-dependent reaction rate that results in a stable detonation wave structure. The detonation is initiated as an ideal Chapman-Jouguet (CJ) detonation with a one-dimensional structure, and then allowed to propagate into a finite diameter or thickness layer of explosive surrounded by an inert layer. The yielding confinement of the inert layer results in the detonation wave decaying to a sub-CJ steady state velocity or failing entirely. Simulations are performed with different values of the reaction rate pressure exponent (n = 2 and 3) and different impedance confinement (greater than, less than, and equal to the confinement of the explosive). The velocity decrement and critical dimension (critical diameter or thickness) are ...

Jianling, Li; Higgins, Andrew J

2014-01-01

66

Studies on Shock Attenuation in Plastic Materials and Applications in Detonation Wave Shaping  

NASA Astrophysics Data System (ADS)

Pressure in plastic materials attenuates due to change of impedance, phase change in the medium and plastic deformation. A lot of theoretical and experimental efforts have been devoted to the attenuation of shock wave produced by the impact of explosive driven flyer plate. However comparatively less work has been done on the attenuation of shock waves due to contact explosive detonation. Present studies deal with the attenuation of explosive driven shock waves in various plastic materials and its applications in design of Hybrid Detonation Wave Generator In present work shock attenuating properties of different polymers such as Perspex, Teflon, nylon, polypropylene and viton has been studied experimentally using rotating mirror streak camera and electrical position pins. High explosive RDX/TNT and OCTOL of diameter 75-100mm and thickness 20 to 50mm were detonated to induce shock wave in the test specimens. From experimental determined shock velocity at different locations the attenuation in shock pressure was calculated. The attenuation of shock velocity with thickness in the material indicates exponential decay according to relation US = UOexp(-ax). In few of the experiments manganin gauge of resistance 50 ohms was used to record stress time profile across shock wave. The shock attenuation data of Viton has successfully been used in the design of hybrid detonation wave generator using Octol as high explosive. While selecting a material it was ensured that the attenuated shock remains strong enough to initiate an acceptor explosive. Theoretical calculation were supported by Autodyne 2D hydro-code simulation which were validated with the experiments conducted using high speed streak photography and electrical shock arrival pins. Shock attenuation data of Perspex was used to establishing card gap test and wedge test in which test items is subjected to known pressure pulse by selecting the thickness of the plastic material.

Khurana, Ritu; Gautam, P. C.; Rai, Rajwant; Kumar, Anil; Sharma, A. C.; Singh, Manjit, Dr

2012-07-01

67

Comparative characteristics of strong shock and detonation waves in bubble media by an electrical wire explosion  

NASA Astrophysics Data System (ADS)

Strong shock and detonation waves in inert and chemically active bubble media, which are generated by a wire explosion initiated by a capacitor with a stored energy W_0 =12.3-1,600 J, is experimentally studied. The measurements are performed near the wire and far from the wire in a vertical shock tube 4.5 m long with a volume fraction of the gas in the medium ? _0 =1-4 %. It is shown that in inert bubble medium, a short intensely decaying shock wave (SW) with intense pressure oscillations is formed in the vicinity of wire explosion point; near the explosion point at ? _0 le 2 % the SW propagates with the velocity of sound in a liquid. In chemically active bubble medium, an unsteady detonation wave generated by a wire explosion is formed. The pressure amplitude and the velocity of this wave are greater and the length is smaller than those of SW in an inert bubble medium in the same range of explosion energy. It is found that in the interval of low energy explosion from {˜ }12 to 64 J, the formation of the bubble detonation wave occurs faster than that at high energies (3× 102-103 J).

Kochetkov, I. I.; Pinaev, A. V.

2013-03-01

68

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

NASA Astrophysics Data System (ADS)

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

Charignon, C.; Chièze, J.-P.

2013-02-01

69

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

NASA Technical Reports Server (NTRS)

Testing and analysis of shock wave characteristics such as 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 gained wide acceptance as the preferred tool for shock measurement. An important asset of VISAR is that it measures velocity and displacement nonintrusively.

Fleming, Kevin J.

1993-01-01

70

Relation Between Spark-Ignition Engine Knock, Detonation Waves, and Autoignition as Shown by High-Speed Photography  

NASA Technical Reports Server (NTRS)

A critical review of literature bearing on the autoignition and detonation-wave theories of spark-ignition engine knock and on the nature of gas vibrations associated with combustion and knock results in the conclusion that neither the autoignition theory nor the detonation-wave theory is an adequate explanation of spark-ignition engine knock. A knock theory is proposed, combining the autoignition and detonation-wave theories, which introduces the idea that the detonation wave develops in autoignited or after-burning gases, and ascribes comparatively low-pitched heavy knocks to autoignition but high-pitched pinging knocks to detonation waves with the possibility of combinations of the two types of knocks. Analysis of five shots of knocking combustion, taken with the NACA high-speed motion-picture camera at the rate of 40,000 photographs per second reveals propagation speeds ranging from 3250 to more than 5500 feet per second. The range of propagation speeds from 3250 to more than 5500 feet per second is held to be considered with the proposed combined theory but not with either the simple autoignition theory or the simple detonation-wave theory.

Miller, Cearcy D

1946-01-01

71

The Attenuation of a Detonation Wave by an Aircraft Engine Axial Turbine Stage  

NASA Technical Reports Server (NTRS)

A Constant Volume Combustion Cycle Engine concept consisting of a Pulse Detonation Combustor (PDC) followed by a conventional axial turbine was simulated numerically to determine the attenuation and reflection of a notional PDC pulse by the turbine. The multi-stage, time-accurate, turbomachinery solver TURBO was used to perform the calculation. The solution domain consisted of one notional detonation tube coupled to 5 vane passages and 8 rotor passages representing 1/8th of the annulus. The detonation tube was implemented as an initial value problem with the thermodynamic state of the tube contents, when the detonation wave is about to exit, provided by a 1D code. Pressure time history data from the numerical simulation was compared to experimental data from a similar configuration to verify that the simulation is giving reasonable results. Analysis of the pressure data showed a spectrally averaged attenuation of about 15 dB across the turbine stage. An evaluation of turbine performance is also presented.

VanZante, Dale; Envia, Edmane; Turner, Mark G.

2007-01-01

72

Analytical and experimental validation of the Oblique Detonation Wave Engine concept  

NASA Technical Reports Server (NTRS)

The Oblique Detonation Wave Engine (ODWE) for hypersonic flight has been analytically studied by NASA using the CFD codes which fully couple finite rate chemistry with fluid dynamics. Fuel injector designs investigated included wall and strut injectors, and the in-stream strut injectors were chosen to provide good mixing with minimal stagnation pressure losses. Plans for experimentally validating the ODWE concept in an arc-jet hypersonic wind tunnel are discussed. Measurements of the flow field properties behind the oblique wave will be compared to analytical predictions.

Adelman, Henry G.; Cambier, Jean-Luc; Menees, Gene P.; Balboni, John A.

1988-01-01

73

Analytical and experimental investigations of the oblique detonation wave engine concept  

NASA Technical Reports Server (NTRS)

Wave combustors, which include the oblique detonation wave engine (ODWE), are attractive propulsion concepts for hypersonic flight. These engines utilize oblique shock or detonation waves to rapidly mix, ignite, and combust the air-fuel mixture in thin zones in the combustion chamber. Benefits of these combustion systems include shorter and lighter engines which require less cooling and can provide thrust at higher Mach numbers than conventional scramjets. The wave combustor's ability to operate at lower combustor inlet pressures may allow the vehicle to operate at lower dynamic pressures which could lessen the heating loads on the airframe. The research program at NASA-Ames includes analytical studies of the ODWE combustor using Computational Fluid Dynamics (CFD) codes which fully couple finite rate chemistry with fluid dynamics. In addition, experimental proof-of-concept studies are being performed in an arc heated hypersonic wind tunnel. Several fuel injection design were studied analytically and experimentally. In-stream strut fuel injectors were chosen to provide good mixing with minimal stagnation pressure losses. Measurements of flow field properties behind the oblique wave are compared to analytical predictions.

Menees, Gene P.; Adelman, Henry G.; Cambier, Jean-Luc

1990-01-01

74

Analytical and experimental investigations of the oblique detonation wave engine concept  

NASA Technical Reports Server (NTRS)

Wave combustors, which include the Oblique Detonation Wave Engine (ODWE), are attractive propulsion concepts for hypersonic flight. These engines utilize oblique shock or detonation waves to rapidly mix, ignite, and combust the air-fuel mixture in thin zones in the combustion chamber. Benefits of these combustion systems include shorter and lighter engines which will require less cooling and can provide thrust at higher Mach numbers than conventional scramjets. The wave combustor's ability to operate at lower combustor inlet pressures may allow the vehicle to operate at lower dynamic pressures which could lessen the heating loads on the airframe. The research program at NASA-Ames includes analytical studies of the ODWE combustor using CFD codes which fully couple finite rate chemistry with fluid dynamics. In addition, experimental proof-of-concept studies are being carried out in an arc heated hypersonic wind tunnel. Several fuel injection designs were studied analytically and experimentally. In-stream strut fuel injectors were chosen to provide good mixing with minimal stagnation pressure losses. Measurements of flow field properties behind the oblique wave are compared to analytical predictions.

Menees, Gene P.; Adelman, Henry G.; Cambier, Jean-Luc

1991-01-01

75

Interaction of disturbances with an oblique detonation wave attached to a wedge  

NASA Technical Reports Server (NTRS)

The linear response of an oblique overdriven detonation to impose free stream disturbances or to periodic movements of the wedge is examined. The free stream disturbances are assumed to be steady vorticity waves and the wedge motions are considered to be time periodic oscillations either about a fixed pivot point or along the plane of symmetry of the wedge aligned with the incoming stream. The detonation is considered to be a region of infinitesimal thickness in which a finite amount of heat is released. The response to the imposed disturbances is a function of the Mach number of the incoming flow, the wedge angle, and the exothermocity of the reaction within the detonation. It is shown that as the degree of overdrive increases, the amplitude of the response increases significantly; furthermore, a fundamental difference in the dependence of the response on the parameters of the problem is found between the response to a free stream disturbance and to a disturbance emanating from the wedge surface.

Lasseigne, D. G.; Hussaini, M. Y.

1993-01-01

76

Reaction Zone Structure of Steady-State Detonation Wave for Tetranitromethane  

NASA Astrophysics Data System (ADS)

The investigation of the reaction zone structure at steady-state detonation in liquid TNM by means of laser interferometer VISAR was conducted. The initial density and detonation velocity of TNM were 1.64 g/cm^3 and 6.4 km/s respectively. Laser beam reflected from Al foil with thickness 7-400 mkm placed between the charge and water window. Velocity profiles with Von Neumann spike were determined. The transition from the reaction zone to unloading wave is smooth and it doesn't allow to define correctly the parameters of Chapman-Jouguet point. Approximate reaction time is 300 ns, and pressure in Von Neumann spike (26,4 GPa) exceeds the pressure in Chapman-Jouguet point (14,5 GPa) 1,8 times. Behind the shock jump a maximum gradient of particle velocity is observed which is equal to 10^7 1/s, it is a typical value for powerful HE. Although TNM has low parameters in Chapman-Jouguet point and a large duration of chemical reaction zone, the high initial decomposition rate provides the existence of steady-state detonation front in tetranitromethane.

Utkin, Alexander; Mochalova, Valentina; Garanin, Victor

2007-06-01

77

Ignition of flamelets behind incident shock waves and the transition to detonation. Memorandum report  

SciTech Connect

Time-dependent numerical simulations are used to elucidate some of the details of weak ignition behind incident shocks and the subsequent transition to detonation. It is shown that a small amount of energy released in the shocked region can be the origin of pressure waves which accelerate the shock front. The simulations presented here show how this leads to the formation of reactive centers. The formation of a hot spot due to energy release at one of the reactive centers and the subsequent development of a pair of flamelets from the hot spot are studied using the numerical simulations. The results of the simulations are also compared to experimental observations.

Kailasanath, K.; Oran, E.S.

1983-03-07

78

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

79

Application of K008 camera within measuring complex of laser diagnostics of shock and detonation waves  

NASA Astrophysics Data System (ADS)

In May 2001 the K008 camera/1,2/ being a part of a laser Doppler velocity meter (LDVM) experimental complex of the Russion Federation Nuclear Center, the All-Russian Research Institute of Experimental Physics (RFNC-VNIIEF), was tested under real conditions of gas-dynamic experiments. Some tasks typical to explosion physics were solved during these experiments: the record of velocities of the plates thrown by an explosion; the record of shock and detonation wave fronts; the record of elastic-plastic properties of constructional materials. At the same time the following camera's characterstics were checke: resistance to electromagnetic, acoustic and light interference; conformity of real characteristics to Documentation data; convenience in operation and reliability.

Lebedev, Vitaly B.; Feldman, Grigory G.; Karpov, Maxim A.; Fedorov, Alexey V.; Menshikh, Alexey V.; Nazarov, Dmitriy V.; Finyushin, Stanislav A.; Davidov, Valeriy A.

2005-03-01

80

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

81

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] [ORNL

2010-01-01

82

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

83

Detonation in Liquid Explosives  

Microsoft Academic Search

DURING the War a general investigation was commenced at the Road Research Laboratory, on the initiative of Dr. A. H. Davis, into the process of detonation in explosives, the programme including a photographic study of the detonation Waves in transparent liquid explosives-the sensitivity of some of which can be varied by adjusting the constitution-and their relation to primers of different

D. Croney

1948-01-01

84

Analytical study of subcritical vapor explosions using thermal detonation wave theory  

SciTech Connect

Experimental observation has shown that the assumption of complete fuel fragmentation in a vapor explosion by the shock adiabatic thermodynamic model results in predicting upper bounds for the shock pressure, propagation velocity, and work output. This model has been modified by considering the condition where the assumption of complete fragmentation of the fuel is relaxed. A methodology is adopted using experimental values of the shock pressure and propagation velocity to estimate the initial mixture conditions of the experiment and the mass fraction of the materials participating in the explosion. Analysis of a steady-state subcritical vapor explosion in one dimension has been carried out by applying the conservation laws of mass, momentum, and energy and the appropriate equation of state for a homogeneous mixture of molten tin and water. The KROTOS-21 experiment, conducted at the Joint Research Center at Ispra, Italy, was used as the initial benchmark experiment in this analysis. A quasi-steady explosion pressure of {approximately}3 MPa and a propagation velocity of {approximately}200 m/s were obtained in this experiment. Using this model, the estimated minimum mass of the fragmented fuel was found to be 0.21 kg (3.2%) of the total mass of the fuel. The predicted work output by this model corresponding to the aforementioned fragmented fuel mass was found to be 9.8 kJ. The estimated initial void fraction of the vapor was found to be 11.5%. In these analyses, a comparison is made of the various possible closure relations applied to the detonation wave theory for a vapor explosion and associated concerns of model stability in the two-phase region.

Shamoun, B.I.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

1996-07-01

85

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

NASA Astrophysics Data System (ADS)

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 expansion was driven by an enormous financial support and two efficient feedbacks: the Terminal Ballistic Cycleand the Research& Development Cycle. Basic knowledge in SWP&DP, initially gained in the Classic Period(from 1808) and further extended in the Post-Classic Period(from the 1930s to present), is now increasingly used also in other branches of Science and Engineering (S&E). However, also independent S&E branches developed, based upon the fundamentals of SWP&DP, many of those developments will be addressed (see Tab. 2). Thus, shock wave and detonation phenomena are now studied within an enormous range of dimensions, covering microscopic, macroscopic, and cosmic dimensions as well as enormous time spans ranging from nano-/picosecond shock durations (such as produced by ultra-short laser pulses) to shock durations that continue for centuries (such as blast waves emitted from ancient supernova explosions). This paper reviews these developments from a historical perspective.

Krehl, Peter O. K.

2011-07-01

86

On the propagation velocity of a detonation-shock combined wave  

NASA Technical Reports Server (NTRS)

A quasi-one-dimensional analysis and a generalized Chapman-Jouguet condition are developed for a gaseous free detonation in an inert environment. Two characteristic features derived from the results are that there exists a lower limit on the heat of combustion, the charge diameter, and the molecular weight of the ambient gas and that there are two propagation velocities for a parameter combination above a certain critical value. Therefore the detonation failure of a free gas column is a hydrodynamic rather than a chemical phenomenon.

Tsuge, S.; Fujiwara, T.

1974-01-01

87

Overheated detonation in condensed explosives  

SciTech Connect

The authors examine the overheating of a chemical detonation wave, which results in hybrid detonation processes, for example, photochemical or electrochemical detonation, depending on the source. The schemes for obtaining the overheated detonation are shown. Analysis has shown that: normal stationary overheated detonation waves are possible when the overheating power density is constant, just as when the specific energy of overheating is constant; the use of the ''gas'' equation of state for describing overheated detonation in condensed explosives yields wave parameters which are too high; and the assumption that the chemical energy released in the explosive is independent of the overheating energy also leads to wave parameters which are too high, and the overestimation increases as the overheating is intensified.

Tarzhanov, V.I.

1986-03-01

88

Optically detonated explosive device  

NASA Technical Reports Server (NTRS)

A technique and apparatus for optically detonating insensitive high explosives, is disclosed. An explosive device is formed by containing high explosive material in a house having a transparent window. A thin metallic film is provided on the interior surface of the window and maintained in contact with the high explosive. A laser pulse provided by a Q-switched laser is focussed on the window to vaporize the metallic film and thereby create a shock wave which detonates the high explosive. Explosive devices may be concurrently or sequentially detonated by employing a fiber optic bundle to transmit the laser pulse to each of the several individual explosive devices.

Yang, L. C.; Menichelli, V. J. (inventors)

1974-01-01

89

Detonation Diffraction into a Confined Volume  

E-print Network

little attention. Experimental work needs to be conducted on detonation diffraction into a confined volume to better understand how the interaction of the diffracted shock wave with a confining wall impacts the detonation diffraction process. Therefore, a...

Polley, Nolan Lee

2012-02-14

90

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

91

A summary of hydrogen-air detonation experiments  

SciTech Connect

Dynamic detonation parameters are reviewed for hydrogen-air-diluent detonations and deflagration-to-detonation transitions (DDT). These parameters include the characteristic chemical length scale, such as the detonation cell width, associated with the three-dimensional cellular structure of detonation waves, critical transmission conditions of confined detonations into unconfined environments, critical initiation energy for unconfined detonations, detonability limits, and critical conditions for DDT. The detonation cell width, which depends on hydrogen and diluent concentrations, pressure, and temperature, is an important parameter in the prediction of critical geometry-dependent conditions for the transmission of confined detonations into unconfined environments and the critical energies for the direct initiation of unconfined detonations. Detonability limits depend on both initial and boundary conditions and the limit has been defined as the onset of single head spin. Four flame propagation regimes have been identified and the criterion for DDT in a smooth tube is discussed. 108 refs., 28 figs., 5 tabs.

Guirao, C.M.; Knystautas, R.; Lee, J.H.

1989-05-01

92

Stability Affects of Artificial Viscosity in Detonation Modeling  

Microsoft Academic Search

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

P Vitello; P C Souers

2002-01-01

93

Two phase detonation studies conducted in 1971  

NASA Technical Reports Server (NTRS)

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

Nicholls, J. A.

1972-01-01

94

Planar Reflection of Gaseous Detonations  

NASA Astrophysics Data System (ADS)

Pipes containing flammable gaseous mixtures may be subjected to internal detonation. When the detonation normally impinges on a closed end, a reflected shock wave is created to bring the flow back to rest. This study built on the work of Karnesky (2010) and examined deformation of thin-walled stainless steel tubes subjected to internal reflected gaseous detonations. A ripple pattern was observed in the tube wall for certain fill pressures, and a criterion was developed that predicted when the ripple pattern would form. A two-dimensional finite element analysis was performed using Johnson-Cook material properties; the pressure loading created by reflected gaseous detonations was accounted for with a previously developed pressure model. The residual plastic strain between experiments and computations was in good agreement. During the examination of detonation-driven deformation, discrepancies were discovered in our understanding of reflected gaseous detonation behavior. Previous models did not accurately describe the nature of the reflected shock wave, which motivated further experiments in a detonation tube with optical access. Pressure sensors and schlieren images were used to examine reflected shock behavior, and it was determined that the discrepancies were related to the reaction zone thickness extant behind the detonation front. During these experiments reflected shock bifurcation did not appear to occur, but the unfocused visualization system made certainty impossible. This prompted construction of a focused schlieren system that investigated possible shock wave-boundary layer interaction, and heat-flux gauges analyzed the boundary layer behind the detonation front. Using these data with an analytical boundary layer solution, it was determined that the strong thermal boundary layer present behind the detonation front inhibits the development of reflected shock wave bifurcation.

Damazo, Jason Scott

95

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.

96

PRELUDE TO A DOUBLE DEGENERATE MERGER: THE ONSET OF MASS TRANSFER AND ITS IMPACT ON GRAVITATIONAL WAVES AND SURFACE DETONATIONS  

SciTech Connect

We present the results of a systematic numerical study of the onset of mass transfer in double degenerate binary systems and its impact on the subsequent evolution. All investigated systems belong to the regime of direct impact, unstable mass transfer. In all of the investigated cases, even those considered unstable by conventional stability analysis, we find a long-lived mass transfer phase continuing for as many as several dozen orbital periods. This settles a recent debate sparked by a discrepancy between earlier smoothed particle hydrodynamics (SPH) calculations that showed disruptions after a few orbital periods and newer grid-based studies in which mass transfer continued for tens of orbits. The number of orbits a binary survives sensitively depends on the exact initial conditions. We find that the approximate initial conditions that have been used in most previous SPH calculations have a serious impact on all stages of the evolution from the onset of mass transfer up to the final structure of the remnant. We compare 'approximate' initial conditions where spherical stars are placed at an initial separation obtained from an estimate of the Roche lobe size with 'accurate' initial conditions that were constructed by carefully driving the binary system to equilibrium by a relaxation scheme. Simulations that use the approximate initial conditions underestimate the initial separation when mass transfer sets in, which yields a binary that only survives for only a few orbits and thus a rapidly fading gravitational wave signal. Conversely, the accurate initial conditions produce a binary system in which the mass transfer phase is extended by almost two orders of magnitude in time, resulting in a gravitational wave signal with amplitude and frequency that remain essentially constant up until merger. As we show that these binaries can survive at small separation for hundreds of orbital periods, their associated gravitational wave signal should be included when calculating the gravitational wave foreground (although expected to be below Laser Interferometer Space Antenna's sensitivity at these high frequencies). We also show that the inclusion of the entropy increase associated with shock heating of the accreted material reduces the number of orbits a binary survives given the same initial conditions, although the effect is not as pronounced when using the appropriate initial conditions. The use of accurate initial conditions and a correct treatment of shock heating allows for a reliable time evolution of the temperature, density, and angular momentum, which are important when considering thermonuclear events that may occur during the mass transfer phase and/or after merger. Our treatment allows us to accurately identify when surface detonations may occur in the lead-up to the merger, as well as the properties of final merger products.

Dan, Marius; Rosswog, Stephan [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany); Guillochon, James; Ramirez-Ruiz, Enrico, E-mail: m.dan@jacobs-university.de, E-mail: rosswog@jacobs-university.de, E-mail: jfg@ucolick.org, E-mail: enrico@ucolick.org [TASC, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2011-08-20

97

Steady Detonation in a Bubbly Medium  

Microsoft Academic Search

It is shown that the Iordanskii–Kogarko model contains a steady-state solution for a detonation wave in chemically active bubbly media under the following minimum requirements to the model: compressibility of the liquid and allowance for acoustic losses. The rule for choosing the velocity is formulated. The wave structure of the reaction zone and the velocity of steady bubble detonation are

S. A. Zhdan

2002-01-01

98

Detonation structures behind oblique shocks  

Microsoft Academic Search

Detonation structures generated by wedge-induced, oblique shocks in hydrogen–oxygen–nitrogen mixtures were investigated by time-dependent numerical simulations. The simulations show a multidimensional detonation structure consisting of the following elements: (1) a nonreactive, oblique shock, (2) an induction zone, (3) a set of deflagration waves, and (4) a ‘‘reactive shock,’’ in which the shock front is closely coupled with the energy release.

Chiping Li; K. Kailasanath; Elaine S. Oran

1994-01-01

99

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

100

Detonation duct gas generator demonstration program  

NASA Technical Reports Server (NTRS)

An experimental demonstration is presented for the generation of detonation waves that move periodically across high speed channel flow; these waves can compress the outflow from a low pressure compressor, and thereby both reduce the compressor requirements associated with conventional gas turbines and enhance thermodynamic efficiency through isochoric energy addition. By generating transient transverse waves, rather than standing waves, shock-wave losses are reduced by an order of magnitude; the result is a Humphrey cycle augmenting the basic Brayton-cycle gas turbine. Attention is presently given to results from an experimental detonation duct.

Wortman, A.; Othmer, P.; Rostafinski, W.

1992-01-01

101

Simple detonation meter  

NASA Astrophysics Data System (ADS)

A new instrument for measuring the detonation factor (sound distortion caused by parasitic frequency modulation within the 0.2 to 200 Hz range) has been built with only three transistors and two microcircuit chips, but it performs as well as the existing commercial 41 instrument. This instrument can operate from any unipolar 14 + or - 1 V d.c. source with a voltage ripple not exceeding 0.5 mV, drawing a maximum current of 25 mA. Its alignment and calibration require only a d.c. voltmeter with 10 kohm/V input resistance and a 3150 Hz sine-wave or square-wave generator. It can then be used for checking tape recorders with the use of test tapes already carrying phonograms of 3150 Hz signals. Three readings must be taken, at the beginning and at the end of a cassette or spool as well as somewhere in the middle, the highest reading being the conclusive one. The detonation factor in the test tape must be smaller than one third of the measured one. The instrument can also be used without test tapes, but the procedure is then more laborious.

Sukhov, N.

1985-01-01

102

Detonation performance of high-dense BTF charges  

NASA Astrophysics Data System (ADS)

New experimental data on detonation wave parameters and explosive performance for benzotrifuroxan are presented. Optical pyrometry was applied in order to measure the temperature and pressure of BTF detonation products. Chapman-Jouguet temperature was obtained as 3990 - 4170 K (charge densities 1.82 - 1.84 g/cc). The heat of explosion and the acceleration ability were measured also. It is also considered the hypothesis of formation of nanodiamond particles in detonation products directly behind the detonation front and influence of these processes on the temperature-time history in detonation products.

Dolgoborodov, A.; Brazhnikov, M.; Makhov, M.; Gubin, S.; Maklashova, I.

2014-05-01

103

Structure and properties of detonation in a liquid-gas buble system  

Microsoft Academic Search

The authors study the detonation of two liquid hydrocarbon fuels, two oils, glycerine and two oxidizers--oxygen and air--in systems with bubbles where the detonation is initiated by the pressure exerted by a detonation wave propagating through the system. They use photography, oscillography, and mathematical simulation to assess the effects of viscosity, pressure, and hydrodynamics on the wave propagation and ignition

A. V. Pinaev; A. I. Sychev

1986-01-01

104

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

105

High-resolution numerical simulation and analysis of Mach reflection structures in detonation waves in low-pressure H2 - O2 - Ar mixtures: a summary of results obtained with the adaptive mesh refinement framework AMROC  

SciTech Connect

Numerical simulation can be key to the understanding of the multi-dimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the non-equilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniques in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, i.e. under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis and a diagram of the transition boundaries between possible Mach reflection structures is constructed.

Deiterding, Ralf [ORNL

2011-01-01

106

Gaseous detonation propagation in a bifurcated tube  

NASA Astrophysics Data System (ADS)

Gaseous detonation propagation in a bifurcated tube was experimentally and numerically studied for stoichiometric hydrogen and oxygen mixtures diluted with argon. Pressure detection, smoked foil recording and schlieren visualization were used in the experiments. Numerical simulation was carried out at low initial pressure (8.00kPa), based on the reactive Navier-Stokes equations in conjunction with a detailed chemical reaction model. The results show that the detonation wave is strongly disturbed by the wall geometry of the bifurcated tube and undergoes a successive process of attenuation, failure, re-initiation and the transition from regular reflection to Mach reflection. Detonation failure is attributed to the rarefaction waves from the left-hand corner by decoupling leading shock and reaction zones. Re-initiation is induced by the inert leading shock reflection on the right-hand wall in the vertical branch. The branched wall geometry has only a local effect on the detonation propagation. In the horizontal branch, the disturbed detonation wave recovers to a self-sustaining one earlier than that in the vertical branch. A critical case was found in the experiments where the disturbed detonation wave can be recovered to be self-sustaining downstream of the horizontal branch, but fails in the vertical branch, as the initial pressure drops to 2.00kPa. Numerical simulation also shows that complex vortex structures can be observed during detonation diffraction. The reflected shock breaks the vortices into pieces and its interaction with the unreacted recirculation region induces an embedded jet. In the vertical branch, owing to the strength difference at any point and the effect of chemical reactions, the Mach stem cannot be approximated as an arc. This is different from the case in non-reactive steady flow. Generally, numerical simulation qualitatively reproduces detonation attenuation, failure, re-initiation and the transition from regular reflection to Mach reflection observed in experiments.

Wang, C. J.; Xu, S. L.; Guo, C. M.

107

Flash x-ray radiography study of the dynamic fracture of metallic discs at the interface between two colliding detonation wave fronts  

NASA Astrophysics Data System (ADS)

In this paper the dynamic fragmentation behavior of a metal disc, positioned at the interface between colliding detonation wave fronts, is investigated. Flash x-ray radiography images from both 150kV and 450kV sytems were obtained to study the break-up phenomena of the metal disc between two similar explosive charges initiated simultaneously. The study was limited to discs of oxygen free high purity copper and an aluminium alloy (6061 T6). During the inititial shock loading phase the disc is stretched accompanied by the formation of spalling fragment rings. At a later stage discrete fragment rings are formed, which fly outward in an expanding disc fashion. The measured discrete fragment velocities ranged between 0.19 mm/?s and 2.7 mm/?s, depending on the material type. Flash x-ray radiography data at specific times is compared with numerical simulations performed using 3D-AutodynTM. Experimental techniques, procedures and results will be presented for the different metals.

Reddy, Kevin J. P.; Terblanche, Cornelis J.; Konig, Pieter J.

2005-03-01

108

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

109

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

110

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

111

The Physical Effects of Detonation in a Closed Cylindrical Chamber  

NASA Technical Reports Server (NTRS)

Detonation in the internal-combustion engine is studied as a physical process. It is shown that detonation is accompanied by pressure waves within the cylinder charge. Sound theory is applied to the calculation of resonant pressure-wave frequencies. Apparatus is described for direct measurement of pressure-wave frequencies. Frequencies determined from two engines of different cylinder sizes are shown to agree with the values calculated from sound theory. An outline of the theoretically possible modes of vibration in a right circular cylinder with flat ends is included. An appendix by John P. Elting gives a method of calculating pressure in the sound wave following detonation.

Draper, C S

1935-01-01

112

Experimental Investigation of Detonation Re-initiation Mechanisms Following a Mach Reflection of a Quenched Detonation  

NASA Astrophysics Data System (ADS)

Detonation waves are supersonic combustion waves that have a multi-shock front structure followed by a spatially non-uniform reaction zone. During propagation, a de-coupled shock-flame complex is periodically re-initiated into an overdriven detonation following a transient Mach reflection process. Past researchers have identified mechanisms that can increase combustion rates and cause localized hot spot re-ignition behind the Mach shock. But due to the small length scales and stochastic behaviour of detonation waves, the important mechanisms that can lead to re-initiation into a detonation requires further clarification. If a detonation is allowed to diffract behind an obstacle, it can quench to form a de-coupled shock-flame complex and if allowed to form a Mach reflection, re-initiation of a detonation can occur. The use of this approach permits the study of re-initiation mechanisms reproducibly with relatively large length scales. The objective of this study is to experimentally elucidate the key mechanisms that can increase chemical reaction rates and sequentially lead to re-initiation of a de-coupled shock-flame complex into an overdriven detonation wave following a Mach reflection. All experiments were carried out in a thin rectangular channel using a stoichiometric mixture of oxy-methane. Three different types of obstacles were used - a half-cylinder, a roughness plate along with the half-cylinder and a full-cylinder. Schlieren visualization was achieved by using a Z-configuration setup, a high speed camera and a high intensity light source. Results indicate that forward jetting of the slip line behind the Mach stem can potentially increase combustion rates by entraining hot burned gas into unburned gas. Following ignition and jet entrainment, a detonation wave first appears along the Mach stem. The transverse wave can form a detonation wave due to rapid combustion of unburned gas which may be attributed to shock interaction with the unburned gas. Alternatively, the Kelvin-Helmholtz instability can produce vortices along the slipline that may lead to mixing between burned-unburned gases and potentially increase combustion rates near the transverse wave. However, the mechanism(s) that causes the transverse wave to re-initiate into a detonation wave remains to be satisfactorily resolved.

Bhattacharjee, Rohit Ranjan

113

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

114

Computation of a diverging Comp-B detonation  

SciTech Connect

The expansion which occurs in diverging detonations weakens the wave and yields pressures and densities below those occurring in planar geometry. We study the problem of a spherically expanding detonation of Comp-B. The effect of varying the order of reaction as well as the rate law parameters (using an Arrhenius burn model) is studied. 14 refs., 3 figs.

Bukiet, B.G.

1989-01-01

115

Multichannel Electronic Counter Chronograph for Determining Detonation Velocities in Explosives  

Microsoft Academic Search

The multichannel time intervalometer (MTI) was designed and fabricated for use in detonation wave measurements. The electronic chronograph was designed to measure short elapsed time events, relative to a start pulse which results from detonation, occurring during relatively long observation periods. The MTI used a quartz crystal as a frequency source and employs high speed transistor components which are capable

H. R. Fuehrer; D. L. Emmons

1968-01-01

116

Structural Response of Piping to Internal Gas Detonation  

Microsoft Academic Search

Detonation waves in gas-filled piping or tubing pose special challenges in analysis and prediction of structural response. The challenges arise due the nature of the detonation process and the role of fluid-structure interaction in determining the prop- agation and arrest of fractures. Over the past ten years, our laboratory has been engaged in studying this problem and devel- oping methodologies

Joseph E. Shepherd

2009-01-01

117

Detonation front in homogeneous and heterogeneous high explosives  

NASA Astrophysics Data System (ADS)

The present report describes the results of experimental researches of detonation wave structure in homogeneous liquid HE: tetranitromethane (TNM), its mixtures with nitromethane and nitrobenzene (TNM/NM, TNM/NB) and plastified compositions based on HMX, RDX, PETN and TNT (heterogeneous HE). Researches were carried out using laser interferometry techniques with nanosecond time resolution. Neumann spike parameters were found for investigated HE. Two types of detonation wave profiles were found in the mixtures of liquid HE based on TNM/NB. Maximums for the registered particle velocity for these profiles differed essentially. Complex 3D-structure of detonation wave front was registered.

Fedorov, A. V.; Zotov, E. V.; Krasovsky, G. B.; Menshikh, A. V.; Yagodin, N. B.

2000-04-01

118

Hydrazine vapor detonations  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

119

Annihilation explosions in macroscopic polyelectrons. Photon detonation  

E-print Network

Annihilation of the electron-positron pairs in macroscopic polyelectrons is considered. It is shown that very fast collapse of the spatial area occupied by macroscopic polyelectron (or dense electron-positron plasma) produces an instant annihilation of a very large number of electron-positron pairs. This phenomenon corresponds to the so-called annihilation explosion. Annihilation of each electron-positron pair is a highly exothermic process. Therefore, in dense electron-positron plasma one can observe a very interesting phenomenon of photon detonation, i.e. a self-organized formation and propagation of the detonation wave which coincides with the annihilation wave. The photon detonation can be used in many applications, including many military and astrophysical problems.

Alexei M. Frolov

2009-06-05

120

Multiphase Detonations in Tubes  

Microsoft Academic Search

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

Sally Cheatham; K. Kailasanath

2002-01-01

121

Bidirectional slapper detonator  

DOEpatents

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

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

1984-01-01

122

Exploding bridgewire detonator simulator  

NASA Technical Reports Server (NTRS)

Tests indicate that electric detonator simulators of the exploding bridgewire type will not fire as a result of the application of a direct current power of one watt for 5 minutes. The detonator also will not fire if the protective gap fails and the firing stimulus is inadvertently applied.

Sullivan, R. R.; Tarley, R. C.; Tarpley, R. C.

1969-01-01

123

Explosive plane-wave lens  

SciTech Connect

An explosive wave lens is described comprising: a. a donor explosive; b. detonator means for generating a detonation wave in the donor explosive; c. an acceptor explosive; d. impactor means for receiving the detonation wave and for striking the acceptor explosive to produce a second detonation wave having a predetermined form in the acceptor explosive; and e. spacer means for spacing the impactor means apart from the acceptor explosive.

Marsh, S.P.

1988-03-08

124

The Stefan problem of detonation theory  

Microsoft Academic Search

A certain model of one-dimensional detonation waves leads to a Stefan problem: the unknown f satisfies Burgers equations on the two sides of a moving discontinuity at which it is given (f, say) and the jump in it derivative (corresponding to the exothermic reaction) is prescribed. An alternative formulation of the problem can be obtained by means of the Hopf-Cole

A. A. Oyediran; G. S. S. Ludford

1985-01-01

125

Gaseous detonation-driven fracture of tubes  

Microsoft Academic Search

An experimental investigation of fracture response of aluminum 6061-T6 tubes under internal gaseous detonation loading has been carried out. The pressure load, with speeds exceeding 2 km\\/s, can be characterized as a pressure peak (ranging from 2 to 6 MPa) followed by an expansion wave. The unique combination of this particular traveling load and tube geometry produced fracture data not

Tong Wa Chao

2004-01-01

126

Pulse Detonation Engine Test Bed Developed  

NASA Technical Reports Server (NTRS)

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

Breisacher, Kevin J.

2002-01-01

127

Shock Wave Initiation of Mixture Liquid Explosives  

NASA Astrophysics Data System (ADS)

We investigated initiation of liquid HE consisting of tetranitromethane (TNM) and nitrobenzene (NB). Smooth stable (when mass of NB<20%) and pulsing unstable detonation wave front was registered (20-50% NB). We registered shock wave, shock compressed explosive (SCE) detonation wave and normal detonation wave for unstable detonation front on different parts of the front. In case of normal and SCE detonation wave we registered parameters rise during 3-25 nsec until the start of chemical reaction. We consider it to be the induction period of thermal explosion inside detonation wave front.

Fedorov, A. V.; Mikhailov, A. L.; Nazarov, D. V.; Finyushin, S. A.; Men'shikh, A. V.; Davydov, V. A.

2006-07-01

128

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

129

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

130

Reignition of detonations by reflected shocks  

NASA Astrophysics Data System (ADS)

Numerical simulations are used to study the diffraction, decay, and reignition that occurs when a detonation propagates past an increase in cross-sectional area in a rectangular tube. The computations solve the time-dependent two-dimensional equations describing a reactive flow in an argon-diluted stoichiometric hydrogen-oxygen mixture at atmospheric pressure. Previous studies have shown that soon after transmission to a larger area, the reaction front decouples from the leading shock and forms a decaying blast wave (“bubble”) in the larger tube. Then, depending on the initial conditions, the detonation either continues to decay or is reignited as the bubble reflects off confining surfaces. For a strongly overdriven initiating detonation, reignition occurs through an interaction between the bubble and the original contact surface. For a more weakly driven system, reignition can occur in two ways: either in the slip line and Mach stem of the Mach reflection formed when the bubble reflects off the bottom surface of the tube, or by multiple shock interactions that occur when the reflected bubble overtakes the initial detonation front. The computations show the evolution and development of the cellular structure of the steady detonation front.

Jones, D. A.; Sichel, M.; Oran, E. S.

1995-06-01

131

Measuring In-Situ Mdf Velocity Of Detonation  

DOEpatents

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

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

2005-10-25

132

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

133

Influence of and additives on acetylene detonation  

NASA Astrophysics Data System (ADS)

The influence of and 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 additive had no influence on the induction time. For , a significant promoting effect was observed. A simplified kinetic model was suggested and characteristic rates of diacetylene 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 pyrolysis, which interacts with acetylene and produces 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.

2014-03-01

134

Detonation structures generated by multiple shocks on ram-accelerator projectiles  

SciTech Connect

The detailed detonation structure generated by multiple shocks on ram-accelerator projectiles is studied using highly resolved numerical simulations. 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 cases, the induction region and the related detonation wave are primarily associated with one single shock. In other cases, the induction region extends across several shocks and the detonation structure is much more complex. These simulations also confirm that the detonations on the projectile are stable in a wide range of flow conditions and, therefore, can be used to generate the high pressure needed for projectile propulsion.

Li, C.; Kailasanath, K.; Oran, E.S. [Naval Research Lab., Washington, DC (United States). Lab. for Computational Physics and Fluid Dynamics] [Naval Research Lab., Washington, DC (United States). Lab. for Computational Physics and Fluid Dynamics

1997-01-01

135

Evaluating detonation possibilities in a Hanford radioactive waste tank  

SciTech Connect

Since the early 1940s, radioactive wastes generated from the defense operations at the Hanford Site have been stored in underground waste storage tanks. During the intervening years, the waste products in some of these tanks have transformed into a potentially hazardous mixture of gases and solids as a result of radiolytic and thermal chemical reactions. One tank in particular, Tank 101-SY, has been periodically releasing high concentrations of a hydrogen/nitrous oxide/nitrogen/ ammonia gas mixture into the tank dome vapor space. There are concerns that under certain conditions a detonation of the flammable gas mixture may occur. There are two ways that a detonation can occur during a release of waste gases into the dome vapor splice: (1) direct initiation of detonation by a powerful ignition source, and (2) deflagration to detonation transition (DDT). The first case involves a strong ignition source of high energy, high power, or of large size (roughly 1 g of high explosive (4.6 kj) for a stoichiometric hydrogen-air mixture{sup 1}) to directly initiate a detonation by ``shock`` initiation. This strong ignition is thought to be incredible for in-tank ignition sources. The second process involves igniting the released waste gases, which results in a subsonic flame (deflagration) propagating into the unburned combustible gas. The flame accelerates to velocities that cause compression waves to form in front of the deflagration combustion wave. Shock waves may form, and the combustion process may transition to a detonation wave.

Travis, J.R.; Fujita, R.K.; Ross, M.C.; Edwards, J.N. [Los Alamos National Lab., NM (United States); Shepherd, J.E. [California Inst. of Tech., Pasadena, CA (United States)

1994-07-01

136

Multiple-cycle Simulation of a Pulse Detonation Engine Ejector  

NASA Technical Reports Server (NTRS)

This paper presents the results of a study involving single and multiple-cycle numerical simulations of various PDE-ejector configurations utilizing hydrogen-oxygen mixtures. The objective was to investigate the thrust, impulse and mass flow rate characteristics of these devices. The results indicate that ejector systems can utilize the energy stored in the strong shock wave exiting the detonation tube to augment the impulse obtained from the detonation tube alone. Impulse augmentation ratios of up to 1.9 were achieved. The axial location of the converging-diverging ejectors relative to the end of the detonation tube were shown to affect the performance of the system.

Yungster, S.; Perkins, H. D.

2002-01-01

137

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

138

Initiation of explosive processes in hydrogen-containing gas mixtures by a multijet flow of detonation products  

Microsoft Academic Search

Explosive regimes initiated by interaction of a detonation wave with a permeable screen are studied experimentally. Possible\\u000a explosive regimes that may form behind the screen are found to be detonation, deflagration-to-detonation transition, quasisteady\\u000a system consisting of the shock wave and the flame front, and decaying shock wave with the flame lagging behind it. The effect\\u000a of the mixture sensitivity and

S. V. Khomik; S. P. Medvedev; B. E. Gel’fand

2010-01-01

139

Detonation Initiators for Propulsion Systems.  

National Technical Information Service (NTIS)

Detonations are an extremely efficient means of burning a fuel-air mixture and converting its chemical energy content into mechanical energy. Air- breathing and rocket engines based on pulsed detonations have the potential to provide the Navy with increas...

C. Li K. Kailasanath

2005-01-01

140

Reverse slapper detonator  

DOEpatents

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

Weingart, Richard C. (Livermore, CA)

1990-01-01

141

Printable sensors for explosive detonation  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

142

On the theory of the propagation of detonation in gaseous systems  

NASA Technical Reports Server (NTRS)

The existing theory of detonation is critically examined. It is shown that the considerations with which the steady value of the velocity of detonation is chosen are not convincing. In connection with the problem of the process of the chemical reaction in a detonation wave, the objections raised against the conceptions of Le Chatelier and Vieille of the 19th century with regard to the ignition of the gas by the shock wave are refuted. On the basis of this concept, it is possible to give a rigorous foundation for the existing method of computing the detonation velocity. The distributions of the temperature, the pressure, and the velocity in the detonation wave front as the chemical reaction proceeds, are considered. On the assumption of the absence of losses, the pure compression of the gas in the shock wave at the start of the chemical reaction develops a temperature that is near the temperature of combustion of the given mixture at constant pressure.

Zeldovich, Y B

1950-01-01

143

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

144

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

145

Minimum tube diameters for steady propagation of gaseous detonations  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

146

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

147

Friction-induced oscillatory behaviour of one-dimensional detonations  

NASA Astrophysics Data System (ADS)

This paper studied the feasibility of the propagation of a steady detonation wave in rough tubes, based on the unsteady quasi-one-dimensional reactive Euler equations with frictional drag. The analysis showed that a competition between the rate of the chemical energy release and the rate of energy dissipation induced by friction drives a detonation in general towards instability. A steady wave solution can exist only when the unsteady downstream flow matches the upstream flow at the sonic locus where this energy rate competition is balanced. This criterion can be satisfied in the presence of low frictional drag. For large frictional drag, the competing effect of the chemical energy release and the momentum loss results in an oscillatory detonation and a steady wave solution does not exist.

Zhang, Fan; Lee, John H. S.

1994-07-01

148

Miniature plasma accelerating detonator and method of detonating insensitive materials  

DOEpatents

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

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

1985-01-04

149

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

150

From combustion and detonation to nitrogen oxides  

NASA Astrophysics Data System (ADS)

This paper looks at Ya B Zeldovich's ideas on the combustion and detonation physics of gaseous mixtures and how they evolved as work in this field progressed. The paper demonstrates the fundamental role of Zeldovich's concept of spontaneous combustion waves in studying transient initiation processes for various combustion regimes and in determining the energy and concentration inflammation limits for combustible gaseous mixtures. It shows how his notion that flame front stretching crucially influences flame acceleration in channels explains in a new way the deflagration-to-detonation transition in highly reactive gaseous mixtures. Most of the presented results were obtained by simulations, allowing Zeldovich's ideas to be extended to the combustion of real gaseous mixtures, where chemical reactions and gasdynamical flows add hugely to the complexity of the problem. The paper concludes by using Zeldovich's mechanism to assess the amount of nitrogen oxide produced by a lightning discharge.

Ivanov, M. F.; Kiverin, A. D.; Klumov, B. A.; Fortov, V. E.

2014-03-01

151

The Use of Steady and Pulsed Detonations for Propulsion Systems  

SciTech Connect

Objectives of the ODWE concept studies are: demonstrate the feasibility of the oblique detonation wave engine (ODWE) for hypersonic propulsion; demonstrate the existance and stability of an oblique detonation wave in hypersonic wind tunnels; develop engineering codes which predict the performance characteristics of the ODWE including specific impulse and thrust coefficients for various operating conditions; develop multi-dimensional computer codes which can model all aspects of the ODWE including fuel injection, mixing, ignition, combustion and expansion with fully detailed chemical kinetics and turbulence models; and validate the codes with experimental data use the simulations to predict the ODWE performance for conditions not easily obtained in wind tunnels.

Adelman, H.G.; Menees, G.P.; Cambier, J.L.; Bowles, J.V.

1996-02-01

152

The Use of Steady and Pulsed Detonations for Propulsion Systems  

NASA Technical Reports Server (NTRS)

Objectives of the ODWE concept studies are: demonstrate the feasibility of the oblique detonation wave engine (ODWE) for hypersonic propulsion; demonstrate the existance and stability of an oblique detonation wave in hypersonic wind tunnels; develop engineering codes which predict the performance characteristics of the ODWE including specific impulse and thrust coefficients for various operating conditions; develop multi-dimensional computer codes which can model all aspects of the ODWE including fuel injection, mixing, ignition, combustion and expansion with fully detailed chemical kinetics and turbulence models; and validate the codes with experimental data use the simulations to predict the ODWE performance for conditions not easily obtained in wind tunnels.

Adelman, Henry G.; Menees, Gene P.; Cambier, Jean-Luc; Bowles, Jeffrey V.

1996-01-01

153

Under consideration for publication in J. Fluid Mech. 1 A numerical study of detonation diffraction  

E-print Network

of the reaction rate to temperature. We study in detail three highly resolved cases of detonation diffraction. The shock wave ignites the reactive material, and the exothermic stage of the reactions creates volume feature in detonation diffraction. For a single-step reaction model of order nr, the rate of reaction

Goddard III, William A.

154

Application of a Schlieren diagnostic to the behavior of exploding bridge wire and laser detonators  

SciTech Connect

Even though the exploding bridge wire (EBW) detonator has been in use for over 60 years, there are still discussions about the mechanism for achieving detonation. Los Alamos has been developing a high-power laser detonator to function in a manner similar to an EBW. Schlieren imaging techniques are applied to laser-driven detonator output in polydimethylsiloxane (POMS) samples to investigate the time-dependent geometry of the shock wave and to obtain instantaneous measurements of shock-front velocity. Velocity Hugoniot data are used to convert measured shock velocities to corresponding particle velocities, allowing instantaneous shock pressures to be obtained via Rankine-Hugoniot relations across the shock.

Murphy, Michael J [Los Alamos National Laboratory; Clarke, Steven A [Los Alamos National Laboratory; Munger, Alan C [Los Alamos National Laboratory; Thomas, Keith A [Los Alamos National Laboratory

2009-01-01

155

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

156

The hydrodynamic theory of detonation  

NASA Technical Reports Server (NTRS)

This report derives equations containing only directly measurable constants for the quantities involved in the hydrodynamic theory of detonation. The stable detonation speed, D, is revealed as having the lowest possible value in the case of positive material velocity, by finding the minimum of the Du curve (u denotes the speed of the gases of combustion). A study of the conditions of energy and impulse in freely suspended detonating systems leads to the disclosure of a rarefaction front traveling at a lower speed behind the detonation front; its velocity is computed. The latent energy of the explosive passes into the steadily growing detonation zone - the region between the detonation front and the rarefaction front. The conclusions lead to a new definition of the concept of shattering power. The calculations are based on the behavior of trinitrotoluene.

Langweiler, Heinz

1939-01-01

157

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.

158

Gaseous detonation initiation and stabilization by hypervelocity projectiles  

NASA Astrophysics Data System (ADS)

An experimental investigation of gaseous detonations initiated and stabilized by high-speed spherical projectiles has been carried out. Detonation initiation by projectiles is closely related to propulsion concepts such as the ram accelerator and the oblique detonation wave engine, in which, theoretically, rapid combustion occurs in detonation waves stabilized on solid objects. The criteria for initiation and stabilization by projectiles are also related to other initiation and propagation criteria such as blast initiation and failure of diffracting detonations. Experimental data of this type are useful for identifying relevant assumptions and important processes, and for providing validation for computational and analytical models. Experiments were performed in the Caltech T5 shock tunnel laboratory. T5 was used in a shock-compression light gas gun mode, with 25.4-mm diameter nylon spheres and velocities around 2300 m/s. Gaseous mixtures studied included 2H2+O2+?N2 (1 >= ? >= 13.76), C2H4+3O2+5N2, and C2H 2+2.5O2+9.4N2 at initial pressures of 0.08-2.56 bar. Flow visualization results obtained by differential interferometry, shadowgraphy, and intensified CCD imaging were augmented by wall pressure records. A wide variety of results were observed, including non- detonative shock-induced combustion, unstably initiated detonations, stabilized prompt initiations, and stabilized delayed initiations. These results can be roughly correlated in terms of the ratio of projectile velocity to mixture Chapman-Jouguet detonation speed, and the ratio of projectile diameter to detonation cell size or reaction zone thickness, although the effects of confinement and unsteadiness complicate this categorization. Two basic approaches to modeling the results have been attempted. In the first, a global model for initiation is based on an existing blast-initiation model using the hypersonic blast-wave analogy. This model is simple, and roughly predicts the experimental results, but suffers from a number of assumptions and approximations that restrict its usefulness and accuracy. The second approach, based on the local shock curvature, is not directly capable of predicting global initiation and failure, but illustrates the mechanism responsible for decoupling of the reaction zone from the shock front in cases of detonation failure. Coupled with a separate model for the shock shape, shock-curvature theory can be used for quantitative global predictions.

Kaneshige, Michael Jiro

159

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

160

Laser supported solid state absorption fronts in silica  

SciTech Connect

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

Carr, C W; Bude, J D

2010-02-09

161

An experimental study of laser supported hydrogen plasmas  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

162

Numerical study of three-dimensional detonation structure transformations in a narrow square tube: from rectangular and diagonal modes into spinning modes  

NASA Astrophysics Data System (ADS)

Three-dimensional (3-D) detonation structure transformations from rectangular and diagonal modes into spinning modes in a narrow square tube are investigated by high-resolution simulation. Numerical simulations are performed with a Riemann solver of the HLLC-type, new cell-based structured adaptive mesh refinement data structure, high-order, parallel adaptive mesh refinement reactive flow code. A simplified one-step kinetic reaction model is used to reveal the 3-D detonation structure. The four different types of initial disturbances applied in the ZND profiles lead to the structures of rectangular in phase, rectangular out of phase, rectangular partial out of phase and diagonal, respectively, during the initial stages of detonation propagation. Eventually, all these detonation structures evolve into the self-sustained spinning detonations. The asymmetric disturbance leads to a stable spinning detonation much faster than the rest. The important features in the formation of spinning detonation are revealed using a 3-D visualization, and a remarkable qualitative agreement with experimental and numerical results is obtained with respect to the transverse wave dynamics and detonation front structures. The transverse wave collisions produce the unburnt gas pockets and the energy to sustain the detonation front propagation and distortion. The periodic pressure oscillation of front plays a complex role as it shifts the reaction zone structure with an accompanying change in the driving energy of transition and the detonation parameters which result in the more distorted front and the unstable detonation. Eventually, the unstable distorted detonation evolves into a spinning detonation.

Huang, Y.; Ji, H.; Lien, F.; Tang, H.

2014-07-01

163

Structure and Stability of One-Dimensional Detonations in Ethylene-Air Mixtures  

NASA Technical Reports Server (NTRS)

The propagation of one-dimensional detonations in ethylene-air mixtures is investigated numerically by solving the one-dimensional Euler equations with detailed finite-rate chemistry. The numerical method is based on a second-order spatially accurate total-variation-diminishing scheme and a point implicit, first-order-accurate, time marching algorithm. The ethylene-air combustion is modeled with a 20-species, 36-step reaction mechanism. A multi-level, dynamically adaptive grid is utilized, in order to resolve the structure of the detonation. Parametric studies over an equivalence ratio range of 0.5 less than phi less than 3 for different initial pressures and degrees of detonation overdrive demonstrate that the detonation is unstable for low degrees of overdrive, but the dynamics of wave propagation varies with fuel-air equivalence ratio. For equivalence ratios less than approximately 1.2 the detonation exhibits a short-period oscillatory mode, characterized by high-frequency, low-amplitude waves. Richer mixtures (phi greater than 1.2) exhibit a low-frequency mode that includes large fluctuations in the detonation wave speed; that is, a galloping propagation mode is established. At high degrees of overdrive, stable detonation wave propagation is obtained. A modified McVey-Toong short-period wave-interaction theory is in excellent agreement with the numerical simulations.

Yungster, S.; Radhakrishnan, K.; Perkins, High D. (Technical Monitor)

2003-01-01

164

Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power  

NASA Technical Reports Server (NTRS)

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

Litchford, Ron J.

2001-01-01

165

Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

166

Semiconductor bridge (SCB) detonator  

DOEpatents

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

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

1999-01-19

167

Light-initiated detonation systems  

Microsoft Academic Search

Numerous light sources could be employed in detonation systems, but lasers have the most efficient coupling to optical fibers and can generate energetic light pulses required for detonation. Flash lamp-pumped, solid state lasers are presently the most useful light source for explosive initiation. Laser diodes in current production cannot generate enough energy for practical applications. The most useful optical fiber

Stafford S. Cooper; Philip G. Malone; Stephen W. Bartholomew; William J. Necker

1986-01-01

168

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

169

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

170

Pulse Detonation Rocket Magnetohydrodynamic Power Experiment  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

171

Detonation Turbulence Interaction L. Massa, M. Chauhan and F. Lu  

E-print Network

zones can be quite large). The influence of transverse waves on detonation and the pattern of quasi energy.3 II. Governing equations The governing equations are the nondimensional conservative form-dimensionalization is obtained using the equations given below, for the nonreactive terms, x i = xi L t = t L/V µ = µ µ

Texas at Arlington, University of

172

Gaseous Detonation-Driven Fracture of Tubes Tong Wa Chao  

E-print Network

literature. Experimental data of this type are useful for studying the fluid- structure-fracture interaction to be consistent with fracture under mixed-mode loading. High-speed movies of the fracture events and blast waveGaseous Detonation-Driven Fracture of Tubes Thesis by Tong Wa Chao In Partial Fulfillment

173

MACH REFLECTION INDUCED DETONATION IN A REACTIVE FLOW  

E-print Network

in this work to show the possibility of the presence of a detonation wave associated with a Mach stem also-implicit treatment of the source terms to obtain a time-accurate solution. In addition, Roe's flux-difference splitting scheme extended to non-equilibrium flow is used for the cell face fluxes, and the MUSCL approach

Texas at Arlington, University of

174

Detonation re-initiation mechanism following the Mach reflection of a quenched detonation  

E-print Network

This experimental study addresses the re-initiation mechanism of detonation waves following the Mach reflection of a shock-flame complex. The detonation diffraction around a cylinder is used to reproducibly generate the shock-flame complex of interest. The experiments are performed in methane-oxygen. We use a novel experimental technique of coupling a two-in-line-spark flash system with a double-frame camera in order to obtain microsecond time resolution permitting accurate schlieren velocimetry. The first series of experiments compares the non-reactive sequence of shock reflections with the reflection over a rough wall under identical conditions. It was found that the hot reaction products generated along the rough wall are entrained by the wall jet into a large vortex structure behind the Mach stem. The second series of experiments performed in more sensitive mixtures addressed the sequence of events leading to the detonation establishment along the Mach and transverse waves. Following ignition and jet entr...

Bhattacharjee, Rohit; Maines, Geoffrey; Maley, Logan; Radulescu, Matei Ioan

2012-01-01

175

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

176

The influence of structural response on sympathetic detonation  

NASA Technical Reports Server (NTRS)

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

Watson, J. L.

1980-01-01

177

Development of an Actuator for Flow Control Utilizing Detonation  

NASA Technical Reports Server (NTRS)

Active flow control devices including mass injection systems and zero-net-mass flux actuators (synthetic jets) have been employed to delay flow separation. These devices are capable of interacting with low-speed, subsonic flows, but situations exist where a stronger crossflow interaction is needed. Small actuators that utilize detonation of premixed fuel and oxidizer should be capable of producing supersonic exit jet velocities. An actuator producing exit velocities of this magnitude should provide a more significant interaction with transonic and supersonic crossflows. This concept would be applicable to airfoils on high-speed aircraft as well as inlet and diffuser flow control. The present work consists of the development of a detonation actuator capable of producing a detonation in a single shot (one cycle). Multiple actuator configurations, initial fill pressures, oxidizers, equivalence ratios, ignition energies, and the addition of a turbulence generating device were considered experimentally and computationally. It was found that increased initial fill pressures and the addition of a turbulence generator aided in the detonation process. The actuators successfully produced Chapman-Jouguet detonations and wave speeds on the order of 3000 m/s.

Lonneman, Patrick J.; Cutler, Andrew D.

2004-01-01

178

Generation of the patterns in gaseous detonations  

NASA Astrophysics Data System (ADS)

The problem addressed here is the mode of formation of the first initial regular pattern and its spacing in a detonation front. It is generally accepted that these patterns derive from a self-sustaining process of formation of Mach stems by colliding blast waves and blast waves from secondary local explosions initiated by these Mach stems. The reason for the very first explosions and their spacing, however, are not known. It is shown here that this is caused by temperature perturbations as they are introduced with any kind of ignition. A steady mode of perturbation is derived which initiates the first local explosions at the extreme end of the combustion zone. They are substitutes for what is considered unrealistic asymptotic decrease. The concept is shown to be in agreement with measurements of the reaction time and of the spacing of soot patterns.

Schultz-Grunow, F.

179

The Los Alamos detonating pellet test (DPT): PBX 9501 evaluation tests  

NASA Astrophysics Data System (ADS)

High explosive (HE) Velocity of Detonation (VOD) measurements are usually conducted using rate-stick-type tests. This method is highly accurate if carefully implemented, but is relatively costly and may require kilograms or more of HE depending on its sensitivity. We present a novel technique for inferring VOD using a single HE pellet, which for Conventional High Explosives (CHEs) can use 10 gm of HE or even less. This attribute makes the Detonating Pellet Test (DPT) ideal for the preliminary performance characterization of newly synthesized HE materials. On the other end of the size spectrum, the DPT can be scaled to very large dimensions so as to minimize the HE load necessary to characterize highly insensitive HEs such as ANFO. The DPT exploits the fact that the detonation emerging from the pellet face can be made highly spherical over some central region. Spherical detonation breakout on the Sample Pellet (SP) face is described by a simple analytic equation, which depends on the VOD and the Center Of Initiation (COI). The latter is determined by separate characterization of the detonator, with a wave refraction correction at the detonator/SP interface. The SP VOD is then determined by fitting the ideal breakout equation, with specified detonator COI, to detonation breakout data obtained via streak camera. We develop the DPT method and appraise it using sample PBX 9501 data in particular, while discussing its benefits and limitations in general.

Preston, D. N.; Hill, L. G.; Tappan, B. C.

2014-05-01

180

Theoretical analysis of rotating two phase detonation in a rocket motor  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

181

Initiation and Detonation of Explosives: An Alternative Concept.  

National Technical Information Service (NTIS)

An observed phenomenon designated as low-velocity detonation is not described properly by the ZND theory of detonation, nor is the deflagration-to-detonation transition, in which a rapidly burning explosive suddenly detonates with no external initiating s...

F. E. Walker

1988-01-01

182

Mechanisms of detonation transmission in layered H2-O2 mixtures  

NASA Astrophysics Data System (ADS)

When a plane detonation propagating through an explosive comes into contact with a bounding explosive, different types of diffraction patterns, which may result in the transmission of a detonation into the bounding mixture, are observed. The nature of these diffraction patterns and the mode of detonation transmission depend on the properties of the primary and bounding explosives. An experimental and analytical study of such diffractions, which are fundamental to many explosive applications, has been conducted in a two channel shock tube, using H2-O2 mixtures of different equivalence ratios as the primary and bounding or secondary explosive. The combination of mixtures was varied from rich primary / lean secondary to lean primary / rich secondary since the nature of the diffraction was found to depend on whether the Chapman-Jouguet velocity of the primary mixture, D p, was greater than or less than that of the secondary mixture, D s. Schlieren framing photographs of the different diffraction patterns were obtained and used to measure shock and oblique detonation wave angles and velocities for the different diffraction patterns, and these were compared with the results of a steady-state shock-polar solution of the diffraction problem. Two basic types of diffraction and modes of detonation reinitiation were observed. When D p> D s, an oblique shock connecting the primary detonation to an oblique detonation in the secondary mixture was observed. With D p< D s, two modes of reinitiation were observed. In some cases, ignition occurs behind the Mach reflection of the shock wave, which is transmitted into the secondary mixture when the primary detonation first comes into contact with it, from the walls of the shock tube. In other cases, a detonation is initiated in the secondary mixture when the reflected shock crosses the contact surface behind the incident detonation. These observed modes of Mach stem and contact surface ignition have also been observed in numerical simulations of layered detonation interactions, as has the combined oblique-shock oblique-detonation configuration when D p> D s. When D p> D s, the primary wave acts like a wedge moving into the secondary mixture with velocity D p after steady state has been reached, a configuration which also arises in oblique-detonation ramjets and hypervelocity drivers.

Tonello, N. A.; Sichel, M.; Kauffman, C. W.

1995-12-01

183

On the neutralization of bacterial spores in post-detonation flows  

NASA Astrophysics Data System (ADS)

In multiple operational scenarios, explosive charges are used to neutralize confined or unconfined stores of bacterial spores. The spore destruction is achieved by post-detonation combustion and mixing of hot detonation product gases with the ambient flow and spore clouds. In this work, blast wave interaction with bacterial spore clouds and the effect of post-detonation combustion on spore neutralization are investigated using numerical simulations. Spherical explosive charges (radius, = 5.9 cm) comprising of nitromethane are modeled in the vicinity of a spore cloud, and the spore kill in the post-detonation flow is quantified. The effect of the mass of the spores and the initial distance, , of the spore cloud from the explosive charge on the percentage of spores neutralized is investigated. When the spores are initially placed within a distance of 3.0, within 0.1 ms after detonation of the charge, all the spores are neutralized by the blast wave and the hot detonation product gases. In contrast, almost all the spores survived the explosion when is greater than 8.0. The percentage of intact spores varied from 0 to 100 for 3.0 8.0 with spore neutralization dependent on time spent by the spores in the post-detonation mixing/combustion zone.

Gottiparthi, K. C.; Schulz, J. C.; Menon, S.

2014-09-01

184

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

185

Effect of surface roughness of charge hole on detonation propagation of emulsion explosive  

SciTech Connect

In the present study, some experimental work was performed to investigate the effects of surface roughness of the charge hole on the velocity of the precursor air shock wave. Photographic observation was performed using rectangular PMMA tubes with sandpaper on inner wall to simulate surface roughness for various decoupling coefficients. The experimental results indicate that the increase of surface roughness of the tube wall reduces the precursor air shock wave velocity and prevents detonation failure. It is shown that detonation failure occurs when the ratio of the precursor air shock wave velocity to detonation velocity becomes greater than 1.21 in the case of a rectangular PMMA tube. Precursor air shock wave velocity and detonation velocity were measured using PVC pipes of various inner diameters with sandpaper on the inner wall to simulate actual charge hole roughness. Sample explosive confined in polyethylene tubes of 20 mm in diameter was placed on the inner wall of the PVC pipe. The experimental results show that the increase of surface roughness of the PVC pipe decreases the velocity of the precursor air shock wave and improves the detonation propagation of explosive in the PVC pipe. It is shown that detonation failure occurs when the ratio of the precursor air shock wave velocity to detonation velocity exceeds 1.1 times in the case of the PVC pipe. The difference observed between the experiments with a rectangular PMMA tube and those with a circular PVC pipe is due to the difference of precompression mode of unreacted explosive by precursor air shock waves.

Sumiya, Fumihiko; Hirosaki, Yoshikazu; Katoh, Yukio [NOF Corp., Aichi (Japan). Explosive and Blasting Research Group; Wada, Yuji; Ogata, Yuji; Katsuyama, Kunihisa [National Inst. for Resources and Environment, Tsukuba, Ibaraki (Japan)

1996-12-01

186

Deflagration-to-Detonation Transition Induced by Hot Jets in a Supersonic Premixed Airstream  

NASA Astrophysics Data System (ADS)

Detonation is initiated through a hot jet in a supersonic premixed mixture of H2 and air, which is produced by using a air heater. The results show that initiation fails in the low-equivalence-ratio premixed gas. With the increase of equivalence ratio, the hot jet can induce deflagration to detonation transition (DDT) in the premixed mixture, which an indirect initiation of detonation. Further studies show that the DDT process is due to the combined effect of a local hemispherical explosion shock wave, the bow shock, and the flame produced by the hot jet.

Han, Xu; Zhou, Jin; Lin, Zhi-Yong; Liu, Yu

2013-05-01

187

A Experimental and Computational Study of the Mechanisms of Detonation Transmission in Layered Hydrogen - Mixtures  

NASA Astrophysics Data System (ADS)

This thesis presents the results of an experimental, analytical, and numerical investigation of the mechanisms of rm H_2-rm O_2 detonation transmission. The experimental configuration is designed to study how a detonation originally propagating into one gaseous mixture of hydrogen and oxygen (primary) is transmitted laterally into a secondary mixture. The configuration and the mixtures used for the experimental and numerical investigations are similar so that the experimental and the numerical results can be compared directly. The experiments are conducted using mixtures with varying equivalence ratios. A stable wave configuration consisting of an oblique shock and an oblique detonation is observed, and three modes of ignition are identified and explained. The analytical results are based on a shock -polar analysis of the steady-state model for the waves in the primary and secondary mixtures, using the two-gamma method of Liou (1986) to derive the jump conditions across the shocks and detonation waves. The analytical method helps interpreting and predicting the experimental results, provided that steady state is achieved. However, numerical simulations are required for the analysis of the early, unsteady part of the transmission. An improved chemical model for rm H_2-rm O_2 combustion is developed and used in one and two-dimensional numerical simulations of detonation waves. The one-dimensional calculations are used to simulate the propagation of a planar detonation wave in a shock tube. The tests of the numerical and physical parameters show that the numerical results agree to within a few percent with the theory of one-dimensional CJ detonations. Two-dimensional simulations of the detonation transmission experiments using the improved chemical model are conducted for the case where both the primary and the secondary mixtures are stoichiometric. In the calculations, the secondary mixture does not ignite behind the transmitted blast wave and the primary detonation gets quenched. Both the absence of ignition in the secondary mixture and the quenching of the primary detonation result from the long ignition times characteristic of the background fluid. In the experiments conducted with both primary and secondary mixtures stoichiometric, the secondary mixture always ignited directly behind the transmitted blast wave. There are at least three possible explanations for the lack of agreement between the numerical and the experimental results: the kinetic model, the physical model (e.g., the transverse waves were not resolved), and discrepancies between the experimental and the simulated problems (e.g., possible presence of three-dimensional effects). These factors suggest that the agreement between the numerical and the experimental results should be improved by increasing the accuracy of the high-pressure kinetic model and the numerical resolution.

Tonello, Nicolas Antoine

188

Stability of cosmological detonation fronts  

NASA Astrophysics Data System (ADS)

The steady-state propagation of a phase-transition front is classified, according to hydrodynamics, as a deflagration or a detonation, depending on its velocity with respect to the fluid. These propagation modes are further divided into three types, namely, weak, Jouguet, and strong solutions, according to their disturbance of the fluid. However, some of these hydrodynamic modes will not be realized in a phase transition. One particular cause is the presence of instabilities. In this work we study the linear stability of weak detonations, which are generally believed to be stable. After discussing in detail the weak detonation solution, we consider small perturbations of the interface and the fluid configuration. When the balance between the driving and friction forces is taken into account, it turns out that there are actually two different kinds of weak detonations, which behave very differently as functions of the parameters. We show that the branch of stronger weak detonations are unstable, except very close to the Jouguet point, where our approach breaks down.

Mégevand, Ariel; Membiela, Federico Agustín

2014-05-01

189

Pulse Detonation Rocket MHD Power Experiment  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

190

Laser system to detonate explosive devices  

NASA Technical Reports Server (NTRS)

Detonating system is not affected by electromagnetic interference. System includes laser source, Q-switch, and optical fiber connected to explosive device. Fiber can be branched out and connected to several devices for simultaneous detonation.

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

1974-01-01

191

Direct Contact Detonation Explosives Metal Forming.  

National Technical Information Service (NTIS)

The forming of hemispheres from flat circular metal blanks by the use of compression forming dies and nitroguanidine detonated in direct contact with the workpiece is described. Direct contact detonation effects are discussed. Relationships between workpi...

J. Savitt, R. E. Conover

1965-01-01

192

Numerical simulations of the cellular structure of detonations in liquid nitromethane - Regularity of the cell structure  

Microsoft Academic Search

The detailed structure of planar detonation waves in liquid nitromethane was studied using time-dependent two-dimensional numerical simulations. The walls are assumed to confine heavily the liquid explosive and boundary layer effects are neglected. The solution thus simulates the detonation structure near the center of a wide channel. Chemical decomposition of nitromethane is described by a two-step model composed of an

R. Guirguis; E. S. Oran; K. Kailasanath

1986-01-01

193

A Virtual Test Facility for Simulating Detonation-Induced Fracture of Thin Flexible Shells  

Microsoft Academic Search

The fluid-structure interaction simulation of detonation- and shock-wave-loaded fracturing thin-walled structures requires numerical methods that can cope with large deformations as well as topology changes. We present a robust level-set-based approach that integrates a Lagrangian thin shell finite element solver with fracture and fragmen- tation capabilities with an Eulerian Cartesian detonation solver with optional dynamic mesh adaptation. As an application

Ralf Deiterding; Fehmi Cirak; Sean Mauch; Daniel I. Meiron

2006-01-01

194

A VIRTUAL TEST FACILITY FOR SIMULATING DETONATION-INDUCED DEFORMATION AND FRACTURE OF THIN FLEXIBLE SHELLS  

Microsoft Academic Search

The fluid-structure interaction simulation of detonation- and shock-wave- loaded fracturing thin-walled structures requires numerical methods that can cope with large deformations as well as topology changes. We present a robust level-set-based approach that integrates a Lagrangian thin shell finite element solver with fracture and fragmenta- tion capabilities with an Eulerian Cartesian detonation solver with optional dynamic mesh adaptation. As computational

Ralf Deiterding; Fehmi Cirak; Sean P. Mauch; Daniel I. Meiron

2006-01-01

195

Gaseous detonation-driven fracture of tubes  

NASA Astrophysics Data System (ADS)

An experimental investigation of fracture response of aluminum 6061-T6 tubes under internal gaseous detonation loading has been carried out. The pressure load, with speeds exceeding 2 km/s, can be characterized as a pressure peak (ranging from 2 to 6 MPa) followed by an expansion wave. The unique combination of this particular traveling load and tube geometry produced fracture data not available before in the open literature. Experimental data of this type are useful for studying the fluid-structure-fracture interaction and various crack curving and branching phenomena, and also for validation for multi-physics and multi-scale modeling. Axial surface flaws were introduced to control the crack initiation site. Fracture threshold models were developed by combining a static fracture model and an extensively studied dynamic amplification factor for tubes under internal traveling loads. Experiments were also performed on hydrostatically loaded preflawed aluminum 6061-T6 tubes for comparison. Significantly different fracture behavior was observed and the difference was explained by fluid dynamics and energy considerations. The experiments yielded comparison on crack speeds, strain, and pressure histories. In other experiments, the specimens were also pre-torqued to control the propagation direction of the cracks. Measurements were made on the detonation velocity, strain history, blast pressure from the crack opening, and crack speeds. The curved crack paths were digitized. The Chapman-Jouguet pressure, initial axial flaw length, and torsion level were varied to obtain different crack patterns. The incipient crack kinking angle was found to be consistent with fracture under mixed-mode loading. High-speed movies of the fracture events and blast wave were taken and these were used in interpreting the quantitative data. Numerical simulations were performed using the commerical explicit finite-element software LS-Dyna. The detonation wave was modeled as a traveling boundary load. Both non-fracturing linear elastic simulations and elastoplastic simulations with fracture were conducted on three-dimensional models. The simulated fracture was compared directly with an experiment with the same conditions. The overall qualitative fracture behavior was captured by the simulation. The forward and backward cracks were observed to branch in both the experiment and simulation.

Chao, Tong Wa

196

Dynamics of oblique detonations in ram accelerators  

Microsoft Academic Search

Time-accurate numerical simulations are used to study the dynamic development of oblique detonations on accelerating projectiles\\u000a in ram accelerators. These simulations show that the oblique detonation can be stabilized on the projectile. The high pressure\\u000a 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

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

1995-01-01

197

Dynamics of oblique detonations in ram accelerators  

Microsoft Academic Search

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

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

1995-01-01

198

PERFORMANCE ENHANCEMENTS ON A PULSED DETONATION ROCKET  

E-print Network

PERFORMANCE ENHANCEMENTS ON A PULSED DETONATION ROCKET The members of the Committee approve #12;To Grandma and Grandpa #12;PERFORMANCE ENHANCEMENTS ON A PULSED DETONATION ROCKET by JASON MATTHEW DETONATION ROCKET Publication No. Jason Matthew Meyers, M.S. The University of Texas at Arlington, 2002

Texas at Arlington, University of

199

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

200

Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector  

NASA Technical Reports Server (NTRS)

Results of an experimental effort on pulse detonation driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE)/ejector setup that was specifically designed for the study and operated at frequencies up to 50 Hz. The results of various experiments designed to probe different aspects of the PDE/ejector setup are reported. The baseline PDE was operated using ethylene (C2H4) as the fuel and an oxygen/nitrogen O2 + N2) mixture at an equivalence ratio of one. The PDE only experiments included propellant mixture characterization using a laser absorption technique, high fidelity thrust measurements using an integrated spring-damper system, and shadowgraph imaging of the detonation/shock wave structure emanating from the tube. The baseline PDE thrust measurement results at each desired frequency agree with experimental and modeling results reported in the literature. These PDE setup results were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups with constant diameter ejector tubes and various ejector lengths, the radius of curvature for the ejector inlets and various detonation tube/ejector tube overlap distances. For the studied experimental matrix, the results showed a maximum thrust augmentation of 106% at an operational frequency of 30 Hz. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

Santoro, Robert J.; Pal, Sibtosh

2005-01-01

201

Deflagration to detonation transition fueled by dust layers  

NASA Astrophysics Data System (ADS)

The roles which dust layers play in severe dust explosions were investigated in a 70 m long and 30 cm inside diameter horizontal Flame Acceleration Tube (FAT) with one end closed and the other end open to the atmosphere. A variety of dusts such as corn dust, cornstarch, Mira Gel starch, wheat dust, and wood flour were layered on the bottom half of the FAT. To initiate the combustion process, a detonation tube filled with a stoichiometric H2/O2 mixture at room temperature and 1 atm pressure was used to ignite a short presuspended dust cloud with a dust concentration of 500 600 g/m3. Combustion waves generated by this dust cloud travel toward the open end of the FAT and are continuously fueled by the dust/air mixtures. Flame propagation processes in the FAT were closely monitored by a variety of measuring instruments at different locations. The study demonstrates that stable quasi-detonation were reached in some runs, but self-sustained Chapman-Jouguet detonations were not observed possibly due to the limitation of the tube length. Attempts were made to determine the structure of dust detonations fueled by a dust layer. Preliminary evidence indicates that for Mira Gel starch the leading shock is essentially a triple shock configuration which involves a Mach stem and for wheat and wood dusts there possibly exists a multi-headed spin structure.

Li, Y.-C.; Harbaugh, A. S.; Alexander, C. G.; Kauffman, C. W.; Sichel, M.

1995-12-01

202

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

203

Airbreathing Pulse Detonation Engine Performance  

NASA Technical Reports Server (NTRS)

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 be significant. These results have an impact on the specific thrust, impulse and fuel consumption of the PDE.

Povinelli, Louis A.; Yungster, Shaye

2002-01-01

204

Sensitized Liquid Hydrazine Detonation Studies  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

205

Pulse detonation engines and components thereof  

NASA Technical Reports Server (NTRS)

A pulse detonation engine comprises a primary air inlet; a primary air plenum located in fluid communication with the primary air inlet; a secondary air inlet; a secondary air plenum located in fluid communication with the secondary air inlet, wherein the secondary air plenum is substantially isolated from the primary air plenum; a pulse detonation combustor comprising a pulse detonation chamber, wherein the pulse detonation chamber is located downstream of and in fluid communication with the primary air plenum; a coaxial liner surrounding the pulse detonation combustor defining a cooling plenum, wherein the cooling plenum is in fluid communication with the secondary air plenum; an axial turbine assembly located downstream of and in fluid communication with the pulse detonation combustor and the cooling plenum; and a housing encasing the primary air plenum, the secondary air plenum, the pulse detonation combustor, the coaxial liner, and the axial turbine assembly.

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

2009-01-01

206

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

SciTech Connect

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

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

2013-07-01

207

Modeling of Multi-Tube Pulse Detonation Engine Operation  

NASA Technical Reports Server (NTRS)

The present paper explores some preliminary issues concerning the operational characteristics of multiple-tube pulsed detonation engines (PDEs). The study is based on a two-dimensional analysis of the first-pulse operation of two detonation tubes exhausting through a common nozzle. Computations are first performed to assess isolated tube behavior followed by results for multi-tube flow phenomena. The computations are based on an eight-species, finite-rate transient flow-field model. The results serve as an important precursor to understanding appropriate propellant fill procedures and shock wave propagation in multi-tube, multi-dimensional simulations. Differences in behavior between single and multi-tube PDE models are discussed, The influence of multi-tube geometry and the preferred times for injecting the fresh propellant mixture during multi-tube PDE operation are studied.

Ebrahimi, Houshang B.; Mohanraj, Rajendran; Merkle, Charles L.

2001-01-01

208

Application of fast infrared detectors to detonation science  

SciTech Connect

Infrared radiometers have been used to make time-resolved emission measurements of shocked explosives. Instruments of moderate time resolution were used to estimate temperatures in shocked but not detonated explosives. The heterogeneity of the shock-induced heating was discovered in pressed explosives by two-band techniques, and the time-resolved emittance or extent of hot spot coverage indicated a great dependence on shock pressures. Temperatures in moderately shocked organic liquids were also measured. Faster response radiometers with 5 ns rise times based on InSb and HgCdTe photovoltaic detectors were constructed and tested. Preliminary data on reactive shocks and detonations reveal a resolution of the heating in the shock wave and the following reaction.

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

1982-07-28

209

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

210

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

211

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

212

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

E-print Network

Curved detonation fronts in solid explosives 1 Curved detonation fronts in solid explosives ###. At the edges of the explosive# D n ### is supplemented with boundary conditons. By direct numerical simulation for simulating complex explosive#containing systems. Key words# Detonation# Curvature e#ect# Edge interactions

Aslam, Tariq

213

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

E-print Network

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

Aslam, Tariq

214

Laser diode initiated detonators for space applications  

NASA Technical Reports Server (NTRS)

Ensign Bickford Aerospace Company (EBAC) has over ten years of experience in the design and development of laser ordnance systems. Recent efforts have focused on the development of laser diode ordnance systems for space applications. Because the laser initiated detonators contain only insensitive secondary explosives, a high degree of system safety is achieved. Typical performance characteristics of a laser diode initiated detonator are described in this paper, including all-fire level, function time, and output. A finite difference model used at EBAC to predict detonator performance, is described and calculated results are compared to experimental data. Finally, the use of statistically designed experiments to evaluate performance of laser initiated detonators is discussed.

Ewick, David W.; Graham, J. A.; Hawley, J. D.

1993-01-01

215

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral...Blasting § 56.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the...

2010-07-01

216

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Compatibility of electric detonators. 57.6400 Section 57.6400 Mineral...Underground § 57.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the...

2010-07-01

217

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 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...

2012-07-01

218

30 CFR 56.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 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...

2011-07-01

219

A nonlinear evolution equation for pulsating detonations using Fickett's model with chain branching kinetics  

E-print Network

The detonation wave stability is addressed using Fickett's equation, i.e., the reactive form of Burgers' equation. This serves as a simple analogue to the reactive Euler equations, permitting one to gain insight into the nonlinear dynamics of detonation waves. Chemical kinetics were modeled using a two-step reaction with distinct induction and reaction zones. An evolution equation for the detonation structure was derived using the method of matched asymptotics for large activation energy and slow rate of energy release. While the first order solution was found unconditionally unstable, the second order evolution equation predicted both stable and unstable solutions. The neutral stability boundary was found analytically, given by $\\chi=4$, where $\\chi$ is the product of activation energy and the ratio of induction to reaction time. This reproduces accurately what has been previously established for the reactive Euler equations and verified experimentally. The evolution equation also captures stable limit cycle...

Bellerive, Andre

2014-01-01

220

Mechanism of deflagration-to-detonation transitions above repeated obstacles  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

221

Detonation diffraction through different geometries  

NASA Astrophysics Data System (ADS)

We performed the study of the diffraction of a self-sustained detonation from a cylindrical tube (of inner diameter d) through different geometric configurations in order to characterise the transmission processes and to quantify the transmission criteria to the reception chamber. For the diffraction from a tube to the open space the transmission criteria is expressed by d c = k c · ? (with ? the detonation cell size and k c depending on the mixture and on the operture configuration, classically 13 for alkane mixtures with oxygen). The studied geometries are: (a) a sharp increase of diameter ( D/ d > 1) with and without a central obstacle in the diffracting section, (b) a conical divergent with a central obstacle in the diffracting section and (c) an inversed intermediate one end closed tube insuring a double reflection before a final diffraction between the initiator tube and the reception chamber. The results for case A show that the reinitiation process depends on the ratio d/ ?. For ratios below k c the re-ignition takes place at the receptor tube wall and at a fixed distance from the step, i.e. closely after the diffracted shock reflection shows a Mach stem configuration. For ratios below a limit ratio k lim (which depends on D/ d) the re-ignition distance increases with the decrease of d/?. For both case A and B the introduction of a central obstacle (of blockage ratio BR = 0.5) at the exit of the initiator tube decreases the critical transmission ratio k c by 50%. The results in configuration C show that the re-ignition process depends both on d/ ? and the geometric conditions. Optimal configuration is found that provides the transmission through the two successive reflections (from d = 26 mm to D ch = 200 mm) at as small d/ ? as 2.2 whatever the intermediate diameter D is. This configuration provides a significant improvement in the detonation transmission conditions.

Sorin, Rémy; Zitoun, Ratiba; Khasainov, Boris; Desbordes, Daniel

2009-04-01

222

Numa Manson on velocity deficits and detonation stability. An invited memorial lecture presented at ICDERS 21  

NASA Astrophysics Data System (ADS)

This memorial paper pays tribute to Professor Numa Manson’s contributions to the understanding of detonation velocity deficits and wave stability. Manson and his colleague Guénoche postulated that a velocity deficit exists in a tube because the chemical reactions are inhibited in a thin layer adjacent to the tube walls. The hydrodynamic theory of detonation was modified to account for this, and it was shown that the deficit varies inversely with the tube diameter. Manson and his students measured detonation velocities in tubes of various diameter. An estimate of the detonation velocity for an infinite tube diameter was obtained by plotting the velocity against the reciprocal of the tube diameter, {?^{-1}} , and extrapolating the line through the data to {?^{-1}=0} . The relative contributions of tube geometry and surface roughness to the deficits were systematically studied. Manson was also one of the early investigators to shed light on the cellular structure of detonation by reporting “vibratory phenomena” seen as striations in streak schlieren photographs. An attempt was made to relate this phenomenon to “dispersions” in the propagation velocity and hence the wave stability. The author has extended Manson’s work by investigating detonations in tubes with yielding walls. Whereas boundary layers were responsible for the gasdynamic expansion and deficits in Manson’s rigid tubes, it was the moving boundaries that caused similar effects in the author’s investigations. The author has repeated the “nozzle” analysis of Fay and Dabora using the detonation cell length as the relevant chemical kinetic length scale, and found reasonable agreement between his experimental results and the model. When the Poitiers data are reinterpreted in light of the modified model, the trends are described quite well. More recent studies have shown that the measured deficits for mixtures characterized by irregular cellular structures do not agree with the Fay-Dabora model. Possible reasons for the discrepancy are discussed.

Murray, S. B.

2008-09-01

223

Tritium labeling of detonation nanodiamonds.  

PubMed

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

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

2014-03-18

224

Numerical simulations of flames and detonations  

Microsoft Academic Search

Time-dependent numerical simulations of multidimensional flames and detonations are discussed in this paper. The differences in the processes which must be modelled and the approaches adopted in simulating flames and detonations are highlighted. A two-dimensional flame model is described and then results of calculations are presented that show the effects of gravity on the structure and propagation of laminar, premixed

K. Kailasanath; E. Oran; J. Boris

225

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

226

Prompt detonation of secondary explosives by laser  

Microsoft Academic Search

Secondary high explosives have been promptly detonated by directing a laser beam of various wavelengths from 266 nanometers to 1.06 micron on the surface of the explosives. For this paper ''prompt'' means the excess transit time through an explosive charge is \\/approximately\\/250 nanoseconds (or less) less than the accepted full detonation velocity time. Timing between laser pulse, explosive initiation and

Paisley

1989-01-01

227

Detonation transfer understanding applied to aerospace problems  

NASA Technical Reports Server (NTRS)

Summary of the findings obtained from a two-year investigation aimed at a quantitative understanding of explosive stimulus transfer. It is felt that the improved understanding achieved on detonation transfer mechanisms will make possible better output tests and specifications, and should result in improved detonators and initiation methods.

Schimmel, M. L.

1974-01-01

228

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

229

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

230

Pulse detonation assembly and hybrid engine  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

231

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

232

Direct Monte Carlo simulation of chemical reaction systems: Prediction of ultrafast detonations  

E-print Network

-dimensional flow with the reaction A MB M having variable energy release and rate characteristics. For a slow by the energy released by exothermic chemical reaction within the wave. A com- plete theoretical treatmentDirect Monte Carlo simulation of chemical reaction systems: Prediction of ultrafast detonations

Anderson, James B.

233

On the existence of multiphase thermal detonations W.W. Yuen, T.G. Theofanous*  

E-print Network

: Microinteractions; Multiphase explosions; Steam explosions; Thermal detonations; Fuel±coolant inter- actions 1 the way for a rational approach to predicting the energetics of such explosions, and indicates the kind physical explosion where the thermal energy of a melt drives and sustains the pressure wave). In complete

Yuen, Walter W.

234

Numerical simulation of detonation failure in nitromethane  

SciTech Connect

Detonation failure in the homogeneous liquid explosive nitromethane has been observed experimentally in a wide variety of confining geometries. However, numerical simulation of these failure situations with a wave propagation code has been essentially non-existent due to the large differences between the critical diameter and the length of the reaction zone - characteristic dimensions which differ by about two orders of magnitude. This inability to spatially resolve both the reaction zone and geometries of significant size has led us to propose a new numerical technique, based on the stability criterion for rate-type material models, in which only temporal resolution of the reaction zone is required. Using an improved model for nitromethane, we have carried out a series of two-dimensional calculations which illustrate the utility of the present approach in predicting a wide range of experimental observations. Of particular computational significance is the removal of the difficulty requiring spatial resolution of the reaction zone, so that problems of practical size can be analyzed with existing computer capabilities.

Kipp, M.E.; Nunziato, J.W.

1981-01-01

235

Influence of ambient air pressure on the energy conversion of laser-breakdown induced blast waves  

NASA Astrophysics Data System (ADS)

Influence of ambient pressure on energy conversion efficiency from a Nd?:?glass laser pulse (? = 1.053 µm) to a laser-induced blast wave was investigated at reduced pressure. Temporal incident and transmission power histories were measured using sets of energy meters and photodetectors. A half-shadowgraph half-self-emission method was applied to visualize laser absorption waves. Results show that the blast energy conversion efficiency ?bw decreased monotonically with the decrease in ambient pressure. The decrease was small, from 40% to 38%, for the pressure change from 101 kPa to 50 kPa, but the decrease was considerable, to 24%, when the pressure was reduced to 30 kPa. Compared with a TEA-CO2-laser-induced blast wave (? = 10.6 µm), higher fraction absorption in the laser supported detonation regime ?LSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ?bw/?LSD?90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case.

Wang, Bin; Komurasaki, Kimiya; Arakawa, Yoshihiro

2013-09-01

236

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

237

Study of detonation initiation in kerosene-oxidizer mixtures in short tubes  

NASA Astrophysics Data System (ADS)

The paper describes experimental studies of detonation initiation in a kerosene-oxidizer mixture in a short test tube. The aim of the study is to determine the minimum diameter of the tube and the minimum level of energy that enables direct initiation of the detonation. Knowledge about these values will inform the design of a jet engine combustion chamber in which thermal energy will be generated by a rotating detonation process. The test tube and the oxidizer inside the tube were heated using specially designed heaters installed outside of the tube. The heated oxidizer provided thermal conditions similar to the conditions for a compressor with small to medium static pressure. The study was conducted for four different tube diameters and for various energies of initiation. As a result, measurements of pressure waveforms were obtained for various cases of fuel injection, which were then compared against the results of the shock wave generated by the initiator. This study provides a value for the energy (the pressure of the mixture in the initiator), which provided direct initiation of detonation for a kerosene-oxidizer mixture. Different tube diameters led to the initiation of detonation for various oxygen-nitrogen compositions as an oxidizer.

Kindracki, J.

2014-11-01

238

Propagation of detonations in hydrazine vapor  

NASA Technical Reports Server (NTRS)

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

Heinrich, H. J.

1985-01-01

239

Theory of weakly nonlinear self sustained detonations  

E-print Network

We propose a theory of weakly nonlinear multi-dimensional self sustained detonations based on asymptotic analysis of the reactive compressible Navier-Stokes equations. We show that these equations can be reduced to a model consisting of a forced, unsteady, small disturbance, transonic equation and a rate equation for the heat release. In one spatial dimension, the model simplifies to a forced Burgers equation. Through analysis, numerical calculations and comparison with the reactive Euler equations, the model is demonstrated to capture such essential dynamical characteristics of detonations as the steady-state structure, the linear stability spectrum, the period-doubling sequence of bifurcations and chaos in one-dimensional detonations and cellular structures in multi- dimensional detonations.

Faria, Luiz M; Rosales, Rodolfo R

2014-01-01

240

Statistical analysis of high explosive detonation data  

SciTech Connect

This study investigates the detonation behavior of two different high explosive compounds, PBX 9404 and PBX 9502. One reason these two high explosives were selected is because data is abundant relative to other types of high explosives. Statistical analysis of data for two different high explosives was performed. The goal of the analysis was to determine how the probability of detonation varies for different run lengths and pressures.

NONE

1998-05-10

241

Chirped fiber Bragg grating detonation velocity sensing.  

PubMed

An all optical-fiber-based approach to measuring high explosive detonation front position and velocity is described. By measuring total light return using an incoherent light source reflected from a linearly chirped fiber Bragg grating sensor in contact with the explosive, dynamic mapping of the detonation front position and velocity versus time is obtained. We demonstrate two calibration procedures and provide several examples of detonation front measurements: PBX 9502 cylindrical rate stick, radial detonation front in PBX 9501, and PBX 9501 detonation along curved meridian line. In the cylindrical rate stick measurement, excellent agreement with complementary diagnostics (electrical pins and streak camera imaging) is achieved, demonstrating accuracy in the detonation front velocity to below the 0.3% level when compared to the results from the pin data. Finally, an estimate on the linear spatial and temporal resolution of the system shows that sub-mm and sub-?s levels are attainable with proper consideration of the recording speed, detection sensitivity, spectrum, and chirp properties of the grating. PMID:23387683

Rodriguez, G; Sandberg, R L; McCulloch, Q; Jackson, S I; Vincent, S W; Udd, E

2013-01-01

242

Chirped fiber Bragg grating detonation velocity sensing  

NASA Astrophysics Data System (ADS)

An all optical-fiber-based approach to measuring high explosive detonation front position and velocity is described. By measuring total light return using an incoherent light source reflected from a linearly chirped fiber Bragg grating sensor in contact with the explosive, dynamic mapping of the detonation front position and velocity versus time is obtained. We demonstrate two calibration procedures and provide several examples of detonation front measurements: PBX 9502 cylindrical rate stick, radial detonation front in PBX 9501, and PBX 9501 detonation along curved meridian line. In the cylindrical rate stick measurement, excellent agreement with complementary diagnostics (electrical pins and streak camera imaging) is achieved, demonstrating accuracy in the detonation front velocity to below the 0.3% level when compared to the results from the pin data. Finally, an estimate on the linear spatial and temporal resolution of the system shows that sub-mm and sub-?s levels are attainable with proper consideration of the recording speed, detection sensitivity, spectrum, and chirp properties of the grating.

Rodriguez, G.; Sandberg, R. L.; McCulloch, Q.; Jackson, S. I.; Vincent, S. W.; Udd, E.

2013-01-01

243

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

244

Propagation Distance Required to Reach Steady-State Detonation Velocity in Finite-Sized Charges  

E-print Network

The decay of a detonation wave from its initial CJ velocity to its final, steady state velocity upon encountering a finite thickness or diameter charge is investigated numerically and theoretically. The numerical simulations use an ideal gas equation of state and pressure dependent reaction rate in order to ensure a stable wave structure. The confinement is also treated as an ideal gas with variable impedance. The velocity decay along the centerline is extracted from the simulations and compared to predictions base on a front evolution equation that uses the steady state detonation velocity-front curvature relation ($D_n-\\kappa$). This model fails to capture the finite signaling speed of the leading rarefaction resulting from the interaction with the yielding confinement. This signaling speed is verified to be the maximum signal velocity occurring in the ideal ZND wave structure of the initial CJ velocity. A simple heuristic model based on the rarefaction generated by a one-dimensional interaction between the...

Li, Jianling; Higgins, Andrew J

2014-01-01

245

Pulse Detonation Engine Air Induction System Analysis  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

246

Computational Study of Near-limit Propagation of Detonation in Hydrogen-air Mixtures  

NASA Technical Reports Server (NTRS)

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.

2002-01-01

247

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

NASA Technical Reports Server (NTRS)

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.

2002-01-01

248

Plasma-assisted ignition and deflagration-to-detonation transition.  

PubMed

Non-equilibrium plasma demonstrates great potential to control ultra-lean, ultra-fast, low-temperature flames and to become an extremely promising technology for a wide range of applications, including aviation gas turbine engines, piston engines, RAMjets, SCRAMjets and detonation initiation for pulsed detonation engines. The analysis of discharge processes shows that the discharge energy can be deposited into the desired internal degrees of freedom of molecules when varying the reduced electric field, E/n, at which the discharge is maintained. The amount of deposited energy is controlled by other discharge and gas parameters, including electric pulse duration, discharge current, gas number density, gas temperature, etc. As a rule, the dominant mechanism of the effect of non-equilibrium plasma on ignition and combustion is associated with the generation of active particles in the discharge plasma. For plasma-assisted ignition and combustion in mixtures containing air, the most promising active species are O atoms and, to a smaller extent, some other neutral atoms and radicals. These active particles are efficiently produced in high-voltage, nanosecond, pulse discharges owing to electron-impact dissociation of molecules and electron-impact excitation of N(2) electronic states, followed by collisional quenching of these states to dissociate the molecules. Mechanisms of deflagration-to-detonation transition (DDT) initiation by non-equilibrium plasma were analysed. For longitudinal discharges with a high power density in a plasma channel, two fast DDT mechanisms have been observed. When initiated by a spark or a transient discharge, the mixture ignited simultaneously over the volume of the discharge channel, producing a shock wave with a Mach number greater than 2 and a flame. A gradient mechanism of DDT similar to that proposed by Zeldovich has been observed experimentally under streamer initiation. PMID:22213667

Starikovskiy, Andrey; Aleksandrov, Nickolay; Rakitin, Aleksandr

2012-02-13

249

Effects of Fuel Distribution on Detonation Tube Performance  

NASA Technical Reports Server (NTRS)

A pulse detonation engine uses a series of high frequency intermittent detonation tubes to generate thrust. The process of filling the detonation tube with fuel and air for each cycle may yield non-uniform mixtures. Uniform mixing is commonly assumed when calculating detonation tube thrust performance. In this study, detonation cycles featuring idealized non-uniform Hz/air mixtures were analyzed using a two-dimensional Navier-Stokes computational fluid dynamics code with detailed chemistry. Mixture non-uniformities examined included axial equivalence ratio gradients, transverse equivalence ratio gradients, and partially fueled tubes. Three different average test section equivalence ratios were studied; one stoichiometric, one fuel lean, and one fuel rich. All mixtures were detonable throughout the detonation tube. Various mixtures representing the same average test section equivalence ratio were shown to have specific impulses within 1% of each other, indicating that good fuel/air mixing is not a prerequisite for optimal detonation tube performance under conditions investigated.

Perkins, H. Douglas; Sung, Chih-Jen

2003-01-01

250

29 CFR 1926.908 - Use of detonating cord.  

...connectors or short-interval-delay electric blasting caps are used with detonating cord, the practice shall...recommendations. (i) When connecting a blasting cap or an electric blasting cap to detonating cord, the cap shall be taped or...

2014-07-01

251

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

252

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

253

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

254

30 CFR 75.1311 - Transporting explosives and detonators.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

255

30 CFR 75.1311 - Transporting explosives and detonators.  

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

2014-07-01

256

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 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...

2012-07-01

257

30 CFR 57.6400 - Compatibility of electric detonators.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 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...

2011-07-01

258

Initiation of detonation regimes in hybrid two-phase mixtures  

Microsoft Academic Search

The problem of detonation initiation is studied in the case of hybrid two-phase mixtures consisting of a hydrogen-air gaseous\\u000a mixture with suspended fine aluminium particles. In preceding works on this subject, investigation of the steady propagation\\u000a regimes has shown that three main propagation regimes could exist: the Pseudo-Gas Detonation (PGD), the Single-Front Detonation\\u000a (SFD), and the Double-Front Detonation (DFD). In

B. A. Khasainov; B. Veyssiere

1996-01-01

259

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

NASA Technical Reports Server (NTRS)

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

Oguz, Sirri

2010-01-01

260

LATERALLY PROPAGATING DETONATIONS IN THIN HELIUM LAYERS ON ACCRETING WHITE DWARFS  

SciTech Connect

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

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

2012-08-10

261

Wave combustors for trans-atmospheric vehicles  

NASA Technical Reports Server (NTRS)

The Wave Combustor is an airbreathing hypersonic propulsion system which utilizes shock and detonation waves to enhance fuel-air mixing and combustion in supersonic flow. In this concept, an oblique shock wave in the combustor can act as a flameholder by increasing the pressure and temperature of the air-fuel mixture and thereby decreasing the ignition delay. If the oblique shock is sufficiently strong, then the combustion front and the shock wave can couple into a detonation wave. In this case, combustion occurs almost instantaneously in a thin zone behind the wave front. The result is a shorter, lighter engine compared to the scramjet. This engine, which is called the Oblique Detonation Wave Engine (ODWE), can then be utilized to provide a smaller, lighter vehicle or to provide a higher payload capability for a given vehicle weight. An analysis of the performance of a conceptual trans-atmospheric vehicle powered by an ODWE is given here.

Menees, Gene P.; Adelman, Henry G.; Cambier, Jean-Luc; Bowles, Jeffrey V.

1989-01-01

262

Deflagration-to-detonation transition in granular HMX  

SciTech Connect

Experimental studies of the deflagration-to-detonation transition (DDT) in chemical explosives, specifically, granular HMX, are reviewed. The picture of the DDT process as presented here results from an attempt to incorporate common experimental observations which have heretofore been puzzling. It differs from that presented by G.B. Kistiakowsky in that the role of convective combustion is terminated and mechanical processes are postulated as the means of continuing the reaction buildup until shock waves are formed. In order to validate this picture it will be necessary both to review the experimental literature for observations which may not be reconcilable with it, and to subject each step in the proposed DDT process to detailed scrutiny. (LCL)

Campbell, A.W.

1980-01-01

263

Axisymmetric Numerical Modeling of Pulse Detonation Rocket Engines  

NASA Technical Reports Server (NTRS)

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

Morris, Christopher I.

2005-01-01

264

Effects of nuclear detonations on the ionosphere  

Microsoft Academic Search

During Operation CASTLE, two ionosphere recorders were operated in the Marshall Islands -at Site Elmer, about 200 miles west of Bikini Atoll, and at Rongerik Atoll, about 150 miles east of Bikini -- in order to study the effects of the detonations on the ionosphere. Severe absorption was observed 200 miles west of all multimegaton shots, lasting several hours, presumably

F. B. Daniels; A. K. Harris

1957-01-01

265

Thermal Ignition of Detonable Hydrogen Peroxide Compositions  

NASA Astrophysics Data System (ADS)

Hydrogen peroxide can be mixed with a variety of fuels to produce detonable compositions. These compositions can be thermally unstable and their behavior can be difficult to predict. Furthermore, the addition of some acids to the mixture could increase its sensitivity. Presented here are the outcome of cookoff experiments performed on hydrogen peroxide and fuels compositions, as well as acid-sensitized mixtures.

Zucker, Jonathan; Foley, Timothy; Dickson, Peter

2009-06-01

266

Screen Secures Detonator to Explosive Charge  

NASA Technical Reports Server (NTRS)

Brass screen sleeve attaches blasting cap to fuse, shaped charge, detonating cord, or other formed explosive. Screen makes it easy to control distance between cap and charge, because user can see both parts, and to cool cap by convection, making use of low-cost blasting caps possible for some hot environments.

Moshenrose, H. D.; Kindsfather, R. A.

1983-01-01

267

EBW's and EFI's: The other electric detonators  

NASA Technical Reports Server (NTRS)

Exploding Bridgewire Detonators (EBW) and Exploding Foil Initiators (EFI) which were originally developed for military applications, have found numerous uses in the non-military commercial market while still retaining their military uses. While not as common as the more familiar hot wire initiators, EBW's and EFI's have definite advantages in certain applications. These advantages, and disadvantages, are discussed for typical designs.

Varosh, Ron

1994-01-01

268

A spectroscopic temperature measurement of converging detonations  

Microsoft Academic Search

Several experimental investigations are reported on converging gaseous detonations with a view toward obtaining a high-temperature plasma and ensuring application to a high-power gasdynamic laser. A microdensitometer is used to analyze the CN violet emission band from the converging point. A method of matching the entire emission spectra is used to determine the temperature at the converging point of a

T. Sugimura; T. Fujiwara

1980-01-01

269

Hydrogen detonation and detonation transition data from the High-Temperature Combustion Facility  

SciTech Connect

The BNL High-Temperature Combustion Facility (HTCF) is an experimental research tool capable of investigating the effects of initial thermodynamic state on the high-speed combustion characteristic of reactive gas mixtures. The overall experimental program has been designed to provide data to help characterize the influence of elevated gas-mixture temperature (and pressure) on the inherent sensitivity of hydrogen-air-steam mixtures to undergo detonation, on the potential for flames accelerating in these mixtures to transition into detonations, on the effects of gas venting on the flame-accelerating process, on the phenomena of initiation of detonations in these mixtures by jets of hot reactant product,s and on the capability of detonations within a confined space to transmit into another, larger confined space. This paper presents results obtained from the completion of two of the overall test series that was designed to characterize high-speed combustion phenomena in initially high-temperature gas mixtures. These two test series are the intrinsic detonability test series and the deflagration-to-detonation (DDT) test series. A brief description of the facility is provided below.

Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.; Gerlach, L. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology; Tagawa, H. [Nuclear Power Engineering Corp., Tokyo (Japan); Malliakos, A. [Nuclear Regulatory Commission, Washington, DC (United States)

1995-12-31

270

Large-Scale Fluid-Structure Interaction Simulation of Viscoplastic and Fracturing Thin Shells Subjected to Shocks and Detonations  

SciTech Connect

The fluid-structure interaction simulation of shock- and detonation-loaded thin-walled structures requires numerical methods that can cope with large deformations as well as local topology changes. We present a robust level-set-based approach that integrates a Lagrangian thin-shell finite element solver with fracture and fragmentation capabilities and an Eulerian Cartesian fluid solver with optional dynamic mesh adaptation. As computational applications, we consider the plastic deformation of a copper plate impacted by a strong piston-induced pressure wave inside a water pipe and the induction of large plastic deformations and rupture of thin aluminum tubes due to the passage of ethylene-oxygen detonations.

Deiterding, Ralf [ORNL

2007-01-01

271

Waves  

E-print Network

WAVES BY Mari LaCure Submitted to the graduate degree program in Visual Art and the Graduate Faculty of the University of Kansas in partial fulfillment of the requirements for the degree of Master’s of Fine Arts. Yoonmi Nam Chairperson... Committee members: Shawn Bitters Michael Krueger Date Defended: March 10, 2010 2 The Thesis Committee for Mari LaCure certifies that this is the approved Version of the following thesis: WAVES...

LaCure, Mari Mae

2010-04-29

272

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

273

Proton radiography of PBX 9502 detonation shock dynamics confinement sandwich test  

SciTech Connect

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

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

2009-01-01

274

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

SciTech Connect

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

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

2010-01-01

275

Proton radiographic and numerical of colliding, diverging PBX-9502 detonations.  

SciTech Connect

The Proton radiographic shot PRAD0077 was designed to study the interaction of colliding, diverging PBX-9502 detonations. The shot consisted of a 50 mm by 50 mm cylinder of PBX-9502 initiated on the top and bottom at the axis by a SE-1 detonator and a 12 mm by 12 mm cylinder of 9407. Seven radiographs were taken at times before and after the detonation collision. The system was modeled using the one-dimensional SIN code with C-J Burn in plane and spherically diverging geometry and using the two-dimensional TDL code with C-J Burn and Forest Fire. The system was also modeled with the recently developed AMR Eulerian reactive hydrodynamic code called NOBEL using Forest Fire. The system results in a large dead or nonreactive zone as the detonation attempts to turn the corner which is described by the model using Forest Fire. The peak detonation pressure achieved by the colliding diverging detonation is 50 gpa and density of 3.125 mg/ml which is about the same as that achieved by one-dimensional spherically diverging 9502 detonations but less than the one-dimensional plane 9502 peak colliding detonation pressure of 65 gpa and density of 3.4 mg/ml. The detonation travels for over 10 mm before it starts to expand and turn the corner leaving more than half of the explosive unreacted. The resulting diverging detonation is more curved than a one-dimensional spherical diverging detonation and has a steeper slope behind the detonation front. This results in the colliding pressure decaying faster than one-dimensional colliding spherical diverging pressures decay. The calculations using Forest Fire reproduce the major features of the radiograph and can be used to infer the colliding detonation characteristics.

Mader, Charles L.; Zumbro, J. D. (John D.); Ferm, E. N. (Eric N.)

2002-01-01

276

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

PubMed Central

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

2013-01-01

277

A Low Cost, Reliable, Hermetically Sealed, Chip Slapper Detonator Suitable for Various Aerospace Applications  

Microsoft Academic Search

EG&G Optoelectronics has developed a low cost, reliable, hermetically sealed, chip slapper detonator for the US Army's anti-tank weapons platforms. This detonator is also qualified and under consideration for several US Navy and Air Force programs. This detonator would also be suitable for various aerospace applications. The design goal for this detonator was to develop a detonator that was as

Barry T. Neyer; John T. Adams; James C. Edwards; Terry S. Stoutenborough; Robert J. Tomasoski

278

Pulse Detonation Engines for High Speed Flight  

NASA Technical Reports Server (NTRS)

Revolutionary concepts in propulsion are required in order to achieve high-speed cruise capability in the atmosphere and for low cost reliable systems for earth to orbit missions. One of the advanced concepts under study is the air-breathing pulse detonation engine. Additional work remains in order to establish the role and performance of a PDE in flight applications, either as a stand-alone device or as part of a combined cycle system. In this paper, we shall offer a few remarks on some of these remaining issues, i.e., combined cycle systems, nozzles and exhaust systems and thrust per unit frontal area limitations. Currently, an intensive experimental and numerical effort is underway in order to quantify the propulsion performance characteristics of this device. In this paper, we shall highlight our recent efforts to elucidate the propulsion potential of pulse detonation engines and their possible application to high-speed or hypersonic systems.

Povinelli, Louis A.

2002-01-01

279

Prompt Reaction of Aluminum in Detonating Explosives  

NASA Astrophysics Data System (ADS)

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

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

2006-07-01

280

Cookoff of Non-Traditional Detonators  

NASA Astrophysics Data System (ADS)

Significant work has gone into understanding the cookoff behavior of a variety of explosives, primarily for safety and surety reasons. However, current times require similar knowledge on a new suite of explosives that are readily attainable or made, and are easily initiated without expensive firesets or controlled materials. Homemade explosives (HMEs) are simple to synthesize from readily available precursor materials. Two of these HMEs, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are not only simple to prepare, but have sufficient output and sensitivity to act as primary explosives in an initiation train. Previous work has shown that detonators may be an integral vulnerability in a cookoff scenario. This poster contains the results of cookoff experiments performed on detonators made with TATP and HMTD. We found that the less chemically stable TATP decomposed during heating, while the more chemically stable HMTD acted like a traditional primary explosive, namely reaction violence and time-to-ignition were independent of confinement.

Zucker, Jonathan; Tappan, Bryce; Manner, Virginia; Novak, Alan

2011-06-01

281

Cookoff of non-traditional detonators  

NASA Astrophysics Data System (ADS)

Significant work has gone into understanding the cookoff behavior of a variety of explosives, primarily for safety and surety reasons. However, current times require similar knowledge on a new suite of explosives that are readily attainable or made, and are easily initiated without expensive firesets or controlled materials. Homemade explosives (HMEs) are simple to synthesize from readily available precursor materials. Two of these HMEs, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) are not only simple to prepare, but have sufficient output and sensitivity to act as primary explosives in an initiation train. Previous work has shown that detonators may be an integral vulnerability in a cookoff scenario. This poster contains the results of cookoff experiments performed on detonators made with TATP and HMTD. We found that the less chemically stable TATP decomposed during heating, while the more chemically stable HMTD acted like a traditional primary explosive, namely reaction violence and time-to-ignition were independent of confinement.

Zucker, Jonathan; Tappan, Bryce C.; Manner, Virginia W.; Novak, Alan

2012-03-01

282

Cable Discharge System for fundamental detonator studies  

NASA Technical Reports Server (NTRS)

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 primary interest are the burst characteristics of these devices when subjected to the constant current pulse delivered by this system. The burst process involves the heating of the bridge material to a conductive plasma and is essential in describing the electrical properties of the bridgewire foil for use in diagnostics or computer models. The CDS described herein is capable of delivering up to an 8000 A pulse of 3 micron duration. Experiments conducted with the CDS to characterize the EBW and EFI burst behavior are also described. In addition, the CDS simultaneous VISAR capability permits updating the EFI electrical Gurney analysis parameters used in our computer simulation codes. Examples of CDS generated data for a typical EFI and EBW detonator are provided.

Peevy, Gregg R.; Barnhart, Steven G.; Brigham, William P.

1994-01-01

283

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

284

Internal ballistics of the detonation products of a blast-hole charge  

SciTech Connect

The authors investigate the gasdynamic flow of the detonation products of a blast-hole charge (the expansion of the detonation products in the blast hole and the gas outflow and propagation of shock airwaves into the face space). The problem is solved by means of a numerical program for integration of partial differential equations of one-dimensional gas-dynamics. A numerical model of the internal ballistics of a blast-hole charge is presented. In addition to the variation of the thermodynamic parameters in the blast hole, the formation of the shock wave in the face space is shown, which is the source of gas ignition. Further development of the numerical model of the action of blast-hole charges is planned which will involve an analysis of a number of applied problems.

Mangush, S.K.; Garbunov, V.A.

1986-07-01

285

Detonation of Meta-stable Clusters  

SciTech Connect

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

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

2008-05-31

286

Hydrodynamic Detonation Instability in Electroweak and QCD Phase Transitions  

E-print Network

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

Mark Abney

1993-05-18

287

Numerical investigation of the physics of rotating-detonation-engines  

Microsoft Academic Search

Rotating-detonation-engines (RDE’s) represent an alternative to the extensively studied pulse-detonation-engines (PDE’s) for obtaining propulsion from the high efficiency detonation cycle. Since it has received considerably less attention, the general flow-field and effect of parameters such as stagnation conditions and back pressure on performance are less well understood than for PDE’s. In this article we describe results from time-accurate calculations of

Douglas Schwer; Kailas Kailasanath

2011-01-01

288

Motivations for laser detonator and firing system developments  

Microsoft Academic Search

For ordnance system and testing applications in which safety is paramount, laser detonators and firing systems are strong candidates. Both low-power (1 W) and high-power (~1 MW) laser-driven explosive devices provide safety against stray current and electrostatic discharges, including lightning. This article addresses only one class of high-power laser-driven detonators that provide prompt detonation - the laser-driven analog of electrical

James E. Kennedy

2006-01-01

289

BNCP prototype detonator studies using a semiconductor bridge initiator  

SciTech Connect

We report on experiments with prototype BNCP detonators incorporating a semiconductor bridge, SCB. We tested two device designs; one for DoD and one for DOE applications. We report tests with the DoD detonator using different firing conditions and two different grain sizes of BNCP. The DOE detonator utilized a 50 {mu}F CDU firing set with a 24 V all-fire condition.

Fyfe, D.W.; Fronabarger, J.W. [Pacific Scientific Co., Avondale-Goodyear, AZ (United States). Energy Dynamics Div.; Bickes, R.W. Jr. [Sandia National Labs., Albuquerque, NM (United States)

1994-06-01

290

THE DETONATION MECHANISM OF THE PULSATIONALLY ASSISTED GRAVITATIONALLY CONFINED DETONATION MODEL OF Type Ia SUPERNOVAE  

SciTech Connect

We describe the detonation mechanism composing the 'pulsationally assisted' gravitationally confined detonation (GCD) model of Type Ia supernovae. This model is analogous to the previous GCD model reported in Jordan et al.; however, the chosen initial conditions produce a substantively different detonation mechanism, resulting from a larger energy release during the deflagration phase. The resulting final kinetic energy and {sup 56}Ni yields conform better to observational values than is the case for the 'classical' GCD models. In the present class of models, the ignition of a deflagration phase leads to a rising, burning plume of ash. The ash breaks out of the surface of the white dwarf, flows laterally around the star, and converges on the collision region at the antipodal point from where it broke out. The amount of energy released during the deflagration phase is enough to cause the star to rapidly expand, so that when the ash reaches the antipodal point, the surface density is too low to initiate a detonation. Instead, as the ash flows into the collision region (while mixing with surface fuel), the star reaches its maximally expanded state and then contracts. The stellar contraction acts to increase the density of the star, including the density in the collision region. This both raises the temperature and density of the fuel-ash mixture in the collision region and ultimately leads to thermodynamic conditions that are necessary for the Zel'dovich gradient mechanism to produce a detonation. We demonstrate feasibility of this scenario with three three-dimensional (3D), full star simulations of this model using the FLASH code. We characterized the simulations by the energy released during the deflagration phase, which ranged from 38% to 78% of the white dwarf's binding energy. We show that the necessary conditions for detonation are achieved in all three of the models.

Jordan, G. C. IV; Graziani, C.; Weide, K.; Norris, J.; Hudson, R.; Lamb, D. Q. [Flash Center for Computational Science, University of Chicago, Chicago, IL 60637 (United States); Fisher, R. T. [Department of Physics, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02740 (United States); Townsley, D. M. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Meakin, C. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Reid, L. B. [NTEC Environmental Technology, Subiaco WA 6008 (Australia)

2012-11-01

291

Simulation of the Reflected Blast Wave froma C-4 Charge  

SciTech Connect

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

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

2011-08-01

292

On the mechanism of the deflagration-to-detonation transition in a hydrogen-oxygen mixture  

SciTech Connect

The flame acceleration and the physical mechanism underlying the deflagration-to-detonation transition (DDT) have been studied experimentally, theoretically, and using a two-dimensional gasdynamic model for a hydrogen-oxygen gas mixture by taking into account the chain chemical reaction kinetics for eight components. A flame accelerating in a tube is shown to generate shock waves that are formed directly at the flame front just before DDT occurred, producing a layer of compressed gas adjacent to the flame front. A mixture with a density higher than that of the initial gas enters the flame front, is heated, and enters into reaction. As a result, a high-amplitude pressure peak is formed at the flame front. An increase in pressure and density at the leading edge of the flame front accelerates the chemical reaction, causing amplification of the compression wave and an exponentially rapid growth of the pressure peak, which 'drags' the flame behind. A high-amplitude compression wave produces a strong shock immediately ahead of the reaction zone, generating a detonation wave. The theory and numerical simulations of the flame acceleration and the new physical mechanism of DDT are in complete agreement with the experimentally observed flame acceleration, shock formation, and DDT in a hydrogen-oxygen gas mixture.

Liberman, M. A., E-mail: misha.liberman@gmail.co [Uppsala University, Department of Physics (Sweden); Ivanov, M. F.; Kiverin, A. D. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Kuznetsov, M. S., E-mail: mike.kuznetsov@kit.ed [Forschungszentrum Karlsruhe (Germany); Rakhimova, T. V.; Chukalovskii, A. A. [Moscow State University, Institute of Nuclear Physics (Russian Federation)

2010-10-15

293

Triple Point Collision and Origin of Unburned Gas Pockets in Irregular Detonations  

E-print Network

The turbulent structure of an irregular detonation is studied through very high resolution numerical simulations of 600 points per half reaction length. The aim is to explore the nature of the transverse waves during the collision and reflection processes of the triple point with the channel walls. Consequently the formation and consumption mechanism of unreacted gas pockets is studied. Results show that as the triple point collides with the wall, the transverse shock interacts with the unreacted pocket. After reflection of the triple point off the wall, the transverse wave interacts with the wall. The structure found to be of a double Mach configuration and does not change before and after reflection. In the second half of the detonation cell the triple point and the transverse wave collide simultaneously with the wall. The strong transverse wave switches from a primary triple point before collision to a new one after reflection. After some time a weak triple point reflects off the wall and hence the structu...

Mahmoudi, Yasser

2014-01-01

294

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

NASA Astrophysics Data System (ADS)

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

Tucker, Kelly Colin

295

Flow Characterization of a Detonation Gun Facility and First Coating Experiments  

NASA Astrophysics Data System (ADS)

A computer-controlled detonation gun based spraying device has been designed and tested to obtain particle velocities over 1200 m/s. The device is able to be operated in two modes based on different flow-physical principles. In one mode, the device functions like a conventional detonation gun in which the powder is accelerated in a blast wave. In the other mode, an extension of the facility with a nozzle uses the detonated gas for an intermittently operated shock tunnel process in which the particles are injected into and accelerated by a quasi-steady high enthalpy nozzle flow with high reservoir conditions. Presented are experimental results of the operation without nozzle in which the device generates moderate to high particle velocities in an intermittent process with a frequency of 5 Hz. A hydrogen/oxygen mixture and Cu and WC-Co (88/12) powders are used in the experiments. Operation performance and tube outflow are characterized by time-resolved Schlieren images and pressure measurements. The particle velocities in the outflow are obtained by laser Doppler anemometry. Different substrate/powder combinations (Al/Cu, Steel/Cu, Al/WC-Co, and Steel/WC-Co) have been investigated by light microscopy and measurements of microhardness.

Henkes, C.; Olivier, H.

2014-06-01

296

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

NASA Astrophysics Data System (ADS)

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

Geier, Stephan

2013-10-01

297

Thermal Ignition of Detonable Hydrogen Peroxide Compositions  

NASA Astrophysics Data System (ADS)

Hydrogen peroxide can be mixed with a variety of fuels to produce detonable compositions. These compositions can be thermally unstable and their behavior can be difficult to predict. Furthermore, the addition of some acids to the mixture could increase its sensitivity. Presented here are the outcomes of cookoff experiments performed on hydrogen peroxide and fuels compositions, as well as an acid-sensitized mixture. Soak temperatures of 88° C, 84° C and 82° C were used, with reaction times of 3010 seconds, 3560 seconds and 3230 seconds, accordingly. The acid-sensitized experiment, when soaked at 82° C, reacted after just 2450 seconds.

Zucker, J. M.; Tappan, B. C.; Lloyd, J. M.; Foley, T. J.

2009-12-01

298

Effects of Fuel Distribution on Detonation Tube Performance  

NASA Technical Reports Server (NTRS)

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

Perkins, Hugh Douglas

2002-01-01

299

Conditions of Experimental Realization of an Electric Detonation  

NASA Astrophysics Data System (ADS)

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

Yankovskiy, Boris

2011-06-01

300

Development of a Large Pulse Detonation Engine Demonstrator  

E-print Network

to achieve deflagration-to-detonation transition (DDT) in as short a distance as possible as this parameter understanding of DDT to the extent that there is sufficient confidence in detonating Professor and Director, California AIAA 2011-5544 Copyright © 2011 by Frank K. Lu. Published by the American Institute of Aeronautics

Texas at Arlington, University of

301

Modelling of detonation cellular structure in aluminium suspensions  

NASA Astrophysics Data System (ADS)

Heterogeneous detonations involving aluminium suspensions have been studied for many years for industrial safety policies, and for military and propulsion applications. Owing to their weak detonability and to the lack of available experimental results on the detonation cellular structure, numerical simulations provide a convenient way to improve the knowledge of such detonations. One major difficulty arising in numerical study of heterogeneous detonations involving suspensions of aluminium particles in oxidizing atmospheres is the modelling of aluminium combustion. Our previous two-step model provided results on the effect on the detonation cellular structure of particle diameter and characteristic chemical lengths. In this study, a hybrid model is incorporated in the numerical code EFAE, combining both kinetic and diffusion regimes in parallel. This more realistic model provides good agreement with the previous two-step model and confirms the correlations found between the detonation cell width, and particle diameter and characteristic lengths. Moreover, the linear dependence found between the detonation cell width and the induction length remains valid with the hybrid model.

Briand, A.; Veyssiere, B.; Khasainov, B. A.

2010-12-01

302

Detonator Performance Characterization Using Multi-Frame Laser Schlieren Imaging  

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. The 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-05099

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

2009-12-01

303

Verification and validation of detonation simulation: topical review  

E-print Network

- , LES, etc.), or reduced/simplified kinetics, flamelet models, could enjoy a graceful retirement when in detonation cal- culation relevant to exercises in V&V: Bhattacharjee, Maines, Maley, & Radulescu: Detonation.) that is difficult to verify and validate via computation today. Let's take a brief historical diversion to a see how

304

DIRECT NUMERICAL SIMULATION OF INTERACTION OF DETONATION WAVE WITH HOMOGENEOUS  

E-print Network

me in both good and bad times of my life. Above all, I offer this success to the almighty God, such as the formation of hot spots. The understanding of such phenomena has practical implications, including in safe

Texas at Arlington, University of

305

Nearly spherical constant power detonation waves driven by focused radiation  

NASA Technical Reports Server (NTRS)

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

George, Y. H.

1973-01-01

306

Determination of detonation parameters for liquid high explosives  

NASA Astrophysics Data System (ADS)

The experimental investigation of detonation parameters and reaction zone structure in liquid HE (bis-(2-fluoro-2,2-dinitroethyl)formal (FEFO), tetranitromethane (TNM), nitromethane (NM)) was conducted by means of laser interferometer VISAR. Detonation front in TNM and NM was stable while the instability of detonation in FEFO was observed. The parameters of Von Neumann spike were determined for these HE. The different methods for C-J point determination were used for each HE. For FEFO reaction time t was found from experiments with different charge diameters (? is approximately equal to 300 ns); for TNM - at fixed diameter and different lengths of charges (? ? 200 ns); for NM - at fixed diameter and length of charges, but detonation initiation was carried out by different explosive charges (? ? 50 ns). It was found that in TNM the detonation velocity depends on charge diameter. Maximum value of reaction rate in investigated liquid HE was observed after shock jump.

Mochalova, Valentina; Utkin, Alexander

2012-03-01

307

Determination of detonation parameters for liquid High Explosives  

NASA Astrophysics Data System (ADS)

The experimental investigation of detonation parameters and reaction zone structure in liquid HE (bis-(2-fluoro-2,2-dinitroethyl)formal (FEFO), tetranitromethane (TNM), nitromethane (NM)) was conducted. Detonation front in TNM and NM was stable while the instability of detonation in FEFO was observed. Von Neumann spike was recorded for these HE and its parameters were determined. The different methods for C-J point determination were used for each HE. For FEFO reaction time ? was found from experiments with different charge diameters (? is approximately equal to 300 ns); for TNM -- at fixed diameter and different lengths of charges (? 200 ns); for NM -- at fixed diameter and length of charges, but detonation initiation was carried out by different explosive charges (? 50 ns). It was found that in TNM the detonation velocity depends on charge diameter. Maximum value of reaction rate in investigated liquid HE was observed after shock jump and induction time was not recorded.

Mochalova, Valentina; Utkin, Alexander

2011-06-01

308

Detonation engine fed by acetylene-oxygen mixture  

NASA Astrophysics Data System (ADS)

The advantages of a constant volume combustion cycle as compared to constant pressure combustion in terms of thermodynamic efficiency has focused the search for advanced propulsion on detonation engines. Detonation of acetylene mixed with oxygen in various proportions is studied using mathematical modeling. Simplified kinetics of acetylene burning includes 11 reactions with 9 components. Deflagration to detonation transition (DDT) is obtained in a cylindrical tube with a section of obstacles modeling a Shchelkin spiral; the DDT takes place in this section for a wide range of initial mixture compositions. A modified ka-omega turbulence model is used to simulate flame acceleration in the Shchelkin spiral section of the system. The results of numerical simulations were compared with experiments, which had been performed in the same size detonation chamber and turbulent spiral ring section, and with theoretical data on the Chapman-Jouguet detonation parameters.

Smirnov, N. N.; Betelin, V. B.; Nikitin, V. F.; Phylippov, Yu. G.; Koo, Jaye

2014-11-01

309

Numerical simulations of the cellular structure of detonations in liquid nitromethane - Regularity of the cell structure  

SciTech Connect

The detailed structure of planar detonation waves in liquid nitromethane was studied using time-dependent two-dimensional numerical simulations. The walls are assumed to confine heavily the liquid explosive and boundary layer effects are neglected. The solution thus simulates the detonation structure near the center of a wide channel. Chemical decomposition of nitromethane is described by a two-step model composed of an induction time followed by energy release. A simplified equation of state based on the Walsh and Christian technique for condensed phases and the BKW equation of state for gas phases is used. When mixtures of both phases are present, pressure and temperature equilibrium between them is assumed. The simulations show a cellular pattern traced by a system of triple points dividing the detonation front into sections. However, a substructure of weaker triple points also traces out a nonuniform pattern within the main pattern, resulting in an irregular cellular structure. A correlation exists between the regularity of the cellular pattern and both the curvature of the front and the change in induction zone thickness at the triple points. If the induction time is a stronger function of temperature, the weaker triple points disappear and a more regular structure is produced. When the structures are regular, the detonation front is more curved and there is a larger change in induction zone thickness at the triple points. However, the large change in induction zone thickness also leads to the formation of unburned pockets that eventually disturb the symmetry and uniformity of the structure. The authors conclude that the regularity of the cellular pattern is strongly influenced by the temperature-dependence of the induction time.

Guirguis, R.; Oran, E.S.; Kailasanath, K.

1986-09-01

310

Unique passive diagnostic for slapper detonators  

NASA Technical Reports Server (NTRS)

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

Brigham, William P.; Schwartz, John J.

1994-01-01

311

Bonfire-safe low-voltage detonator  

DOEpatents

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

Lieberman, M.L.

1988-07-01

312

High-gain inertial confinement fusion by volume ignition, avoiding the complexities of fusion detonation fronts of spark ignition  

Microsoft Academic Search

Summary form only given, as follows. The main approach to inertial confinement fusion (ICF) uses a high-temperature, low-density core and a high-density, low-temperature outer region of the laser(or ion beam-) compressed deuterium-tritium (D-T) fuel, in order to ignite a fusion detonation wave at the interface. This is an extremely delicate, unstable configuration which is very difficult to achieve, even with

H. Hora; S. Eliezer; J. J. Honrubia; R. Hopfl; J. M. Martinez-Val; G. H. Miley; G. Velarde

1995-01-01

313

Deflagration-to-detonation in granular HMX: Ignition, kinetics, and shock formation  

SciTech Connect

Experimental studies and analysis of the deflagration-to detonation transition (DDT) in granular HMX are continued. Experiments performed using a direct-gasless igniter exhibit the same phenomenology as those ignited with a piston. Simple kinetics and mechanics describe the formation of the {approximately}100% TMD plug in terms of competing pressurization processes. A mass-conservation analysis of the experimentally observed structures shows how the low velocities characteristic of convective burning are amplified to shock-wave velocities through non-convective processes.

McAfee, J.M.; Asay, B.W.; Bdzil, J.B.

1993-06-01

314

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

NASA Astrophysics Data System (ADS)

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

Ravindran, Prashaanth

315

Recent papers from DX-1, detonation science and technology  

SciTech Connect

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

NONE

1996-10-01

316

Impurity-doped optical shock, detonation and damage location sensor  

DOEpatents

A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack.

Weiss, Jonathan D. (Albuquerque, NM)

1995-01-01

317

Impurity-doped optical shock, detonation and damage location sensor  

DOEpatents

A shock, detonation, and damage location sensor providing continuous fiber-optic means of measuring shock speed and damage location, and could be designed through proper cabling to have virtually any desired crush pressure. The sensor has one or a plurality of parallel multimode optical fibers, or a singlemode fiber core, surrounded by an elongated cladding, doped along their entire length with impurities to fluoresce in response to light at a different wavelength entering one end of the fiber(s). The length of a fiber would be continuously shorted as it is progressively destroyed by a shock wave traveling parallel to its axis. The resulting backscattered and shifted light would eventually enter a detector and be converted into a proportional electrical signals which would be evaluated to determine shock velocity and damage location. The corresponding reduction in output, because of the shortening of the optical fibers, is used as it is received to determine the velocity and position of the shock front as a function of time. As a damage location sensor the sensor fiber cracks along with the structure to which it is mounted. The size of the resulting drop in detector output is indicative of the location of the crack. 8 figs.

Weiss, J.D.

1995-02-07

318

Model for Shock Wave Chaos  

E-print Network

We propose the following model equation, u[subscript t]+1/2(u[superscript 2]-uu[subscript s])[subscript x]=f(x,u[subscript s]) that predicts chaotic shock waves, similar to those in detonations in chemically reacting ...

Kasimov, Aslan R.

319

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

320

Numerical Modeling of Pulse Detonation Rocket Engine Gasdynamics and Performance  

NASA Technical Reports Server (NTRS)

Pulse detonation engines (PDB) have generated considerable research interest in recent years as a chemical propulsion system potentially offering improved performance and reduced complexity compared to conventional gas turbines and rocket engines. The detonative mode of combustion employed by these devices offers a theoretical thermodynamic advantage over the constant-pressure deflagrative combustion mode used in conventional engines. However, the unsteady blowdown process intrinsic to all pulse detonation devices has made realistic estimates of the actual propulsive performance of PDES problematic. The recent review article by Kailasanath highlights some of the progress that has been made in comparing the available experimental measurements with analytical and numerical models.

Morris, C. I.

2003-01-01

321

Propagation of nitromethane detonations in porous media  

NASA Astrophysics Data System (ADS)

The characteristics of the propagation of a detonation in chemically sensitized nitromethane in a dense porous medium are investigated. By introducing liquid NM+15% (by weight) DETA into densely packed beds of solid spherical glass beads 66?m to 2.4 mm in diameter, a highly heterogeneous explosive mixture is obtained. The critical (i.e., failure) charge diameter of this mixture is systematically measured in unconfined charges over a wide range of bead sizes. Velocity measurements are also made for the various charges. It is found that there exists a critical bead size above which the critical diameter decreases with increasing bead size and below which it decreases with decreasing bead size. This result indicates an abrupt change in the mechanism of propagation at the critical bead size. Velocity measurements further support this by emphasizing the different behavior above and below the critical point.

Lee, J. J.; Frost, D. L.; Lee, J. H. S.; Dremin, A.

1995-06-01

322

Molecular Dynamics Simulation of Shock Induced Detonation  

NASA Astrophysics Data System (ADS)

This research focuses on molecular dynamics (MD) simulation of shock induced detonation in Fe2O3+Al thermite mixtures. A MD model is developed to simulate non-equilibrium stress-induced reactions. The focus is on establishing a criterion for reaction initiation, energy content and rate of energy release as functions of mixture and reinforcement characteristics. A cluster functional potential is proposed for this purpose. The potential uses the electronegativity equalization to account for changes in the charge of different species according to local environment. Parameters in the potential are derived to fit to the properties of Fe, Al, Fe2O3, and Al2O3. NPT MD simulations are carried out to qualitatively check the energetics of the forward (Fe2O3+Al) as well as backward (Al2O3+Fe) thermite reactions. The results show that the potential can account for the energetics of thermite reactions.

Tomar, Vikas; Zhou, Min

2004-07-01

323

A Mechanistic Study of Delayed Detonation in Impact Damaged Solid Rocket Propellant  

Microsoft Academic Search

One method of hazard assessment for mass detonable solid rocket propellants consists of impacting right circular cylinders of propellant end-on into thick steel witness plates at varying impact velocities. A detonation that occurs within one shock traversal of the cylinder length is termed a prompt detonation or a shock-to-detonation transition (SDT). At lower velocities, some propellants detonate at times later

E. R. Matheson; J. T. Rosenberg

2002-01-01

324

Spark-safe low-voltage detonator  

DOEpatents

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

Lieberman, M.L.

1988-07-01

325

Blasting detonators incorporating semiconductor bridge technology  

SciTech Connect

The enormity of the coal mine and extraction industries in Russia and the obvious need in both Russia and the US for cost savings and enhanced safety in those industries suggests that joint studies and research would be of mutual benefit. The author suggests that mine sites and well platforms in Russia offer an excellent opportunity for the testing of Sandia`s precise time-delay semiconductor bridge detonators, with the potential for commercialization of the detonators for Russian and other world markets by both US and Russian companies. Sandia`s semiconductor bridge is generating interest among the blasting, mining and perforation industries. The semiconductor bridge is approximately 100 microns long, 380 microns wide and 2 microns thick. The input energy required for semiconductor bridge ignition is one-tenth the energy required for conventional bridgewire devices. Because semiconductor bridge processing is compatible with other microcircuit processing, timing and logic circuits can be incorporated onto the chip with the bridge. These circuits can provide for the precise timing demanded for cast effecting blasting. Indeed tests by Martin Marietta and computer studies by Sandia have shown that such precise timing provides for more uniform rock fragmentation, less fly rock, reduce4d ground shock, fewer ground contaminants and less dust. Cost studies have revealed that the use of precisely timed semiconductor bridges can provide a savings of $200,000 per site per year. In addition to Russia`s vast mineral resources, the Russian Mining Institute outside Moscow has had significant programs in rock fragmentation for many years. He anticipated that collaborative studies by the Institute and Sandia`s modellers would be a valuable resource for field studies.

Bickes, R.W. Jr.

1994-05-01

326

Evolution of autocorrelation in detonation interaction with homogeneous,  

E-print Network

shock­turbulence interaction (STI) due to exothermicity, and the presence of a detonation lengthscale and is the reaction progress variable with 0 being the unburnt state and 1 the completely burnt state. The definition

Texas at Arlington, University of

327

Delayed detonation in propellants from low-velocity impact  

SciTech Connect

Certain high HMX-content propellants are found to undergo delayed detonation when cylinders of the propellant are subjected to axisymetric impact. The magnitude of the impact pressure is considerably less than that required for prompt shock initiation. It is also found that granular propellant (65 to 78% theoretical maximum density) packed in a thick-walled (50 mm) Plexiglas pipe is easily detonated by relatively low-velocity (130 m/s) piston compaction of the porous propellant. The above processes appear to be related to each other and to the more classical deflagration-to-detonation studies carried out in heavy-walled pipes where the explosive is deliberately ignited to start the build-up to detonation.

Green, L.G.; James, E.; Lee, E.L.; Chambers, E.S.; Tarver, C.M.; Westmoreland, C.; Weston, A.M.; Brown, B.

1981-01-01

328

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

E-print Network

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

Rodriguez, Alejandro W.

329

Frequency content of current pulses in slapper detonator bridges  

SciTech Connect

DFT amplitudes are obtained for digital current pulse files. The frequency content of slapper detonator bridge current pulses is obtained. The frequencies are confined well within the passband of the CVR used to sample them.

Carpenter, K H

2006-12-18

330

Explosive plane-wave lens  

DOEpatents

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

Marsh, Stanley P. (Los Alamos, NM)

1988-01-01

331

Explosive plane-wave lens  

DOEpatents

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

Marsh, S.P.

1987-03-12

332

Explosive plane-wave lens  

DOEpatents

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

Marsh, S.P.

1988-03-08

333

LASERS: Iodine laser pumped by light from a shock front created by detonating an explosive  

NASA Astrophysics Data System (ADS)

The results are presented of investigations, performed in 1965-1966, of a pulsed photodissociation iodine laser utilizing CF3I and C3F7I molecules and pumped by light from a shock front created by detonating an explosive charge. Such lasers were found to possess a unique combination of high output energy and high pulse power. Two types of laser were studied. In one of them the active medium was pumped by light from a shock wave in xenon, and in the other a shock wave propagated through a mixture of the active medium and a rare gas. The energy characteristics of the second type of laser were found to be considerably higher than those of the first type. The laser pulse radiation enegy reached ~100 J with an average power of ~15 MW.

Arzhanov, V. P.; Borovich, Boris L.; Zuev, V. S.; Kazanski?, V. M.; Katulin, V. A.; Kirillov, G. A.; Kormer, S. B.; Kuratov, Yu V.; Kuryapin, A. I.; Nosach, O. Yu; Sinitsyn, M. V.; Sto?lov, Yu Yu

1992-02-01

334

What is a shock wave to an explosive molecule?*  

NASA Astrophysics Data System (ADS)

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

Tarver, Craig

2001-06-01

335

Simulation of a Spherical Wave Experiment in Marble Using a Multidirectional Damage Model.  

National Technical Information Service (NTIS)

This paper presents experimental results and computational simulations of spherical wave propagation in Danby marble. The experiment consisted of a 2-cm-diameter explosive charge detonated in the center of a cylindrical rock sample. Radial particle veloci...

T. H. Antoun, I. N. Lomov

2003-01-01

336

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

337

HERMES: A Model to Describe Deformation, Burning, Explosion, and Detonation  

SciTech Connect

HERMES (High Explosive Response to MEchanical Stimulus) was developed to fill the need for a model to describe an explosive response of the type described as BVR (Burn to Violent Response) or HEVR (High Explosive Violent Response). Characteristically this response leaves a substantial amount of explosive unconsumed, the time to reaction is long, and the peak pressure developed is low. In contrast, detonations characteristically consume all explosive present, the time to reaction is short, and peak pressures are high. However, most of the previous models to describe explosive response were models for detonation. The earliest models to describe the response of explosives to mechanical stimulus in computer simulations were applied to intentional detonation (performance) of nearly ideal explosives. In this case, an ideal explosive is one with a vanishingly small reaction zone. A detonation is supersonic with respect to the undetonated explosive (reactant). The reactant cannot respond to the pressure of the detonation before the detonation front arrives, so the precise compressibility of the reactant does not matter. Further, the mesh sizes that were practical for the computer resources then available were large with respect to the reaction zone. As a result, methods then used to model detonations, known as {beta}-burn or program burn, were not intended to resolve the structure of the reaction zone. Instead, these methods spread the detonation front over a few finite-difference zones, in the same spirit that artificial viscosity is used to spread the shock front in inert materials over a few finite-difference zones. These methods are still widely used when the structure of the reaction zone and the build-up to detonation are unimportant. Later detonation models resolved the reaction zone. These models were applied both to performance, particularly as it is affected by the size of the charge, and to situations in which the stimulus was less than that needed for reliable performance, whether as a result of accident, hazard, or a fault in the detonation train. These models describe the build-up of detonation from a shock stimulus. They are generally consistent with the mesoscale picture of ignition at many small defects in the plane of the shock front and the growth of the resulting hot-spots, leading to detonation in heterogeneous explosives such as plastic-bonded explosives (PBX). The models included terms for ignition, and also for the growth of reaction as tracked by the local mass fraction of product gas, {lambda}. The growth of reaction in such models incorporates a form factor that describes the change of surface area per unit volume (specific surface area) as the reaction progresses. For unimolecular crystalline-based explosives, the form factor is consistent with the mesoscale picture of a galaxy of hot spots burning outward and eventually interacting with each other. For composite explosives and propellants, where the fuel and oxidizer are segregated, the diffusion flame at the fuel-oxidizer interface can be interpreted with a different form factor that corresponds to grains burning inward from their surfaces. The form factor influences the energy release rate, and the amount of energy released in the reaction zone. Since the 19th century, gun and cannon propellants have used perforated geometric shapes that produce an increasing surface area as the propellant burns. This helps maintain the pressure as burning continues while the projectile travels down the barrel, which thereby increases the volume of the hot gas. Interior ballistics calculations use a geometric form factor to describe the changing surface area precisely. As a result, with a suitably modified form factor, detonation models can represent burning and explosion in damaged and broken reactant. The disadvantage of such models in application to accidents is that the ignition term does not distinguish between a value of pressure that results from a shock, and the same pressure that results from a more gradual increase. This disagrees with experiments, where

Reaugh, J E

2011-11-22

338

Deflagration to detonation experiments in granular HMX  

SciTech Connect

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

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

1998-03-01

339

Reducing the Consequences of a Nuclear Detonation.  

SciTech Connect

The 2002 National Strategy to Combat Weapons of Mass Destruction states that 'the United States must be prepared to respond to the use of WMD against our citizens, our military forces, and those of friends and allies'. Scenario No.1 of the 15 Department of Homeland Security national planning scenarios is an improvised nuclear detonation in the national capitol region. An effective response involves managing large-scale incident response, mass casualty, mass evacuation, and mass decontamination issues. Preparedness planning activities based on this scenario provided difficult challenges in time critical decision making and managing a large number of casualties within the hazard area. Perhaps even more challenging is the need to coordinate a large scale response across multiple jurisdictions and effectively responding with limited infrastructure and resources. Federal response planning continues to make improvements in coordination and recommending protective actions, but much work remains. The most critical life-saving activity depends on actions taken in the first few minutes and hours of an event. The most effective way to reduce the enormous national and international social and economic disruptions from a domestic nuclear explosion is through planning and rapid action, from the individual to the federal response. Anticipating response resources for survivors based on predicted types and distributions of injuries needs to be addressed.

Buddemeier, B R

2007-11-09

340

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

NASA Astrophysics Data System (ADS)

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

Henkes, C.; Olivier, H.

2014-04-01

341

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

SciTech Connect

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

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

1994-05-01

342

Measurements of the DDT Process in Exploding Bridgewire Detonators  

NASA Astrophysics Data System (ADS)

The deflagration-to-detonation transition (DDT) of low density (0.88 g/cc) PETN during exploding bridgewire (EBW) initiation has been studied using laser interferometry and streak photography. Cutback experiments using VISAR have confirmed a 1.0 mm run-distance to detonation in this low density PETN powder. In a detonation system using a combination of low and high density powders, an apparent center of initiation (COI) analysis of streak data has yielded a surprisingly similar result. This data suggested that a compaction of low density powder to near theoretical maximum density (TMD) may occur before the onset of detonation, which is consistent with work done previously. These experiments show this is not the case and COI analysis reveals a non-ideal initial propagation front. Additionally, data show that although function time increases significantly with decreasing firing voltage, the apparent COI changes very little. This indicates that the detonation criterion is not dependent upon the rate of deflagration, but on a volume of material that must be burned in a confined space to create the critical pressure needed at the compaction front.

Martin, Eric S.; Thomas, Keith A.; Clarke, Steven A.; Kennedy, James E.; Stewart, D. Scott

2006-07-01

343

A Performance Map for Ideal Air Breathing Pulse Detonation Engines  

NASA Technical Reports Server (NTRS)

The performance of an ideal, air breathing Pulse Detonation Engine is described in a manner that is useful for application studies (e.g., as a stand-alone, propulsion system, in combined cycles, or in hybrid turbomachinery cycles). It is shown that the Pulse Detonation Engine may be characterized by an averaged total pressure ratio, which is a unique function of the inlet temperature, the fraction of the inlet flow containing a reacting mixture, and the stoichiometry of the mixture. The inlet temperature and stoichiometry (equivalence ratio) may in turn be combined to form a nondimensional heat addition parameter. For each value of this parameter, the average total enthalpy ratio and total pressure ratio across the device are functions of only the reactant fill fraction. Performance over the entire operating envelope can thus be presented on a single plot of total pressure ratio versus total enthalpy ratio for families of the heat addition parameter. Total pressure ratios are derived from thrust calculations obtained from an experimentally validated, reactive Euler code capable of computing complete Pulse Detonation Engine limit cycles. Results are presented which demonstrate the utility of the described method for assessing performance of the Pulse Detonation Engine in several potential applications. Limitations and assumptions of the analysis are discussed. Details of the particular detonative cycle used for the computations are described.

Paxson, Daniel E.

2001-01-01

344

CHEETAH: A fast thermochemical code for detonation  

SciTech Connect

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

Fried, L.E.

1993-11-01

345

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

NASA Technical Reports Server (NTRS)

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

Paxson, Daniel E.

2003-01-01

346

Effects of Non-Uniform Fuel Distribution on Detonation Tube Performance  

NASA Technical Reports Server (NTRS)

A pulse detonation engine uses a series of high frequency intermittent detonation tubes to generate thrust. The process of filling the detonation tube with fuel and air for each cycle may yield non-uniform mixtures. Uniform mixing is commonly assumed when calculating detonation tube thrust performance. In this study, detonation cycles featuring idealized non-uniform H2/air mixtures were analyzed using a two-dimensional Navier-Stokes computational fluid dynamics code with detailed chemistry. Mixture non-uniformities examined included axial equivalence ratio gradients, transverse equivalence ratio gradients, and partially fueled tubes. Three different average test section equivalence ratios were studied; one stoichiometric, one fuel lean, and one fuel rich. All mixtures were detonable throughout the detonation tube. Various mixtures representing the same average test section equivalence ratio were shown to have specific impulses within 1% of each other, indicating that good fuel/air mixing is not a prerequisite for optimal detonation tube performance under the conditions investigated.

Perkins, H. Douglas; Sung, Chih-Jen

2003-01-01

347

49 CFR 178.318 - Specification MC 201; container for detonators and percussion caps.  

Code of Federal Regulations, 2011 CFR

...false Specification MC 201; container for detonators and percussion caps. 178.318 Section 178.318 Transportation Other Regulations...318 Specification MC 201; container for detonators and percussion...

2011-10-01

348

49 CFR 178.318 - Specification MC 201; container for detonators and percussion caps.  

Code of Federal Regulations, 2012 CFR

...false Specification MC 201; container for detonators and percussion caps. 178.318 Section 178.318 Transportation Other Regulations...318 Specification MC 201; container for detonators and percussion...

2012-10-01

349

49 CFR 178.318 - Specification MC 201; container for detonators and percussion caps.  

Code of Federal Regulations, 2013 CFR

...false Specification MC 201; container for detonators and percussion caps. 178.318 Section 178.318 Transportation Other Regulations...318 Specification MC 201; container for detonators and percussion...

2013-10-01

350

49 CFR 178.318 - Specification MC 201; container for detonators and percussion caps.  

Code of Federal Regulations, 2010 CFR

...false Specification MC 201; container for detonators and percussion caps. 178.318 Section 178.318 Transportation Other Regulations...318 Specification MC 201; container for detonators and percussion...

2010-10-01

351

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

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Detonation arresters, flame arresters, and flame screens. 154.822 Section 154.822 Navigation...Control Systems § 154.822 Detonation arresters, flame arresters, and flame screens. (a) Each...

2013-07-01

352

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

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false Detonation arresters, flame arresters, and flame screens. 154.822 Section 154.822 Navigation...Control Systems § 154.822 Detonation arresters, flame arresters, and flame screens. (a) Each...

2011-07-01

353

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

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false Detonation arresters, flame arresters, and flame screens. 154.822 Section 154.822 Navigation...Control Systems § 154.822 Detonation arresters, flame arresters, and flame screens. (a) Each...

2012-07-01

354

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

355

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

356

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

357

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

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

2014-07-01

358

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

359

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

360

30 CFR 75.1313 - Explosives and detonators outside of magazines.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

361

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

362

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

363

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

364

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

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

2014-07-01

365

30 CFR 75.1312 - Explosives and detonators in underground magazines.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

366

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

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

2014-07-01

367

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

368

30 CFR 75.1328 - Damaged or deteriorated explosives and detonators.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

369

Parametric Study of High Frequency Pulse Detonation Tubes  

NASA Technical Reports Server (NTRS)

This paper describes development of high frequency pulse detonation tubes similar to a small pulse detonation engine (PDE). A high-speed valve injects a charge of a mixture of fuel and air at rates of up to 1000 Hz into a constant area tube closed at one end. The reactants detonate in the tube and the products exit as a pulsed jet. High frequency pressure transducers are used to monitor the pressure fluctuations in the device and thrust is measured with a balance. The effects of injection frequency, fuel and air flow rates, tube length, and injection location are considered. Both H2 and C2H4 fuels are considered. Optimum (maximum specific thrust) fuel-air compositions and resonant frequencies are identified. Results are compared to PDE calculations. Design rules are postulated and applications to aerodynamic flow control and propulsion are discussed.

Cutler, Anderw D.

2008-01-01

370

Synthesis of carbon-coated iron nanoparticles by detonation technique  

SciTech Connect

Carbon-coated iron nanoparticles were synthesized by detonating a mixture of ferrocene, naphthalene and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in an explosion vessel under low vacuum conditions (8.1 kPa). The RDX functioned as an energy source for the decomposition of ferrocene and naphthalene. The carbon-coated iron nanoparticles were formed as soot-like deposits on the inner surface of the reactor, which were characterized by XRD, TEM, HRTEM, Raman spectroscopy and vibrating sample magnetometer. And a portion of the detonation soot was treated with hydrochloric acid. The product was carbon-coated nanoparticles in perfect core-shell structures with graphitic shells and bcc-Fe cores. The detonation technique offers an energy-saving route to the synthesis of carbon-coated nanomaterials.

Sun, Guilei, E-mail: sunguilei@126.com [Department of Safety Engineering, China Institute of Industrial Relations, Beijing 100037 (China)] [Department of Safety Engineering, China Institute of Industrial Relations, Beijing 100037 (China); Li, Xiaojie, E-mail: dalian03@vip.sina.com [State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023 (China)] [State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023 (China); Wang, Qiquan [Department of Safety Engineering, China Institute of Industrial Relations, Beijing 100037 (China)] [Department of Safety Engineering, China Institute of Industrial Relations, Beijing 100037 (China); Yan, Honghao [State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023 (China)] [State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023 (China)

2010-05-15

371

Ferrite core coupled slapper detonator apparatus and method  

DOEpatents

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

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

1989-01-01

372

Ferrite core coupled slapper detonator apparatus and method  

DOEpatents

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

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

1989-08-01

373

Flying-plate detonator using a high-density high explosive  

DOEpatents

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

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

1988-01-01

374

Energy Output of Insensitive High Explosives by Measuring the Detonation Products  

Microsoft Academic Search

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

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

1992-01-01

375

Characterization of Detonation Products of RSI-007 Explosive  

NASA Astrophysics Data System (ADS)

PDV and VISAR have been employed to characterize the detonation products of a production quality RSI-007 explosive. The explosive was part of an exploding foil initiator (EFI) detonator assembly in which the explosive was contained within a Kovar (Fe-Ni-Co alloy) cup. The free surface of the Kovar serves as the witness plate for the interferometry measurements. Detailed shock reverberations are recorded on the witness plate and the isentropic release path of the explosive is inferred though the velocity history. Two separate window materials are bonded to the Kovar cup in subsequent experiments and are used to further determine the release state in different pressure regimes.

Ager, Timothy; Neel, Christopher; Chhabildas, Lalit

2011-06-01

376

Characterization of detonation products of RSI-007 explosive  

NASA Astrophysics Data System (ADS)

PDV and VISAR have been employed to characterize the detonation products of a high-purity CL-20 based explosive. The explosive was part of an exploding foil initiator (EFI) detonator assembly in which the explosive was contained within a Kovar (Fe-Ni-Co alloy) cup. The back surface of the Kovar serves as the witness plate for interferometry measurements. Detailed reverberations corresponding to shock arrival and release are recorded on the witness plate and the isentropic release path of the explosive is inferred though the velocity history. Two separate window materials are bonded to the Kovar cup in subsequent experiments and are used to further refine the release states.

Ager, Timothy; Neel, Christopher; Breaux, Bradley; Vineski, Christopher; Welle, Eric; Lambert, David; Chhabildas, Lalit

2012-03-01

377

Experimental study of spark-discharge initiation of detonation  

NASA Astrophysics Data System (ADS)

The mechanisms of action on a high-current spark discharge that make it possible to reduce the total expenditure of electric energy on initiating detonation have been proposed. The action is based on the control of a discharge current with the aid of an external circuit and on the addition of easily ionizable admixtures to a fuel-oxygen mixture. Results of experimental investigations into the spark-discharge initiation of detonation with the action on the discharge process have been presented; the results were obtained in mixtures of hydrogen with oxygen and of commercial propane-butane with oxygen at atmospheric pressure.

Korytchenko, K. V.; Golota, V. I.; Kudin, D. V.; Rodionov, S. V.

2013-05-01

378

An exact solution for axial flow in cylindrically symmetric, steady-state detonation in polytropic explosive with an arbitrary rate of decomposition  

Microsoft Academic Search

Methods of differential geometry and Bernoulli’s equation, written as B=0, are used to develop a new approach for constructing an exact solution for axial flow in a classical, two-dimensional, ZND detonation wave in a polytropic explosive with an arbitrary rate of decomposition. This geometric approach is fundamentally different from the traditional approaches to this axial flow problem formulated by Wood

M. Cowperthwaite

1994-01-01

379

Temperature activated absorption during laser-induced damage: The evolution of laser-supported solid-state absorption fronts  

SciTech Connect

Previously we have shown that the size of laser induced damage sites in both KDP and SiO{sub 2} is largely governed by the duration of the laser pulse which creates them. Here we present a model based on experiment and simulation that accounts for this behavior. Specifically, we show that solid-state laser-supported absorption fronts are generated during a damage event and that these fronts propagate at constant velocities for laser intensities up to 4 GW/cm{sup 2}. It is the constant absorption front velocity that leads to the dependence of laser damage site size on pulse duration. We show that these absorption fronts are driven principally by the temperature-activated deep sub band-gap optical absorptivity, free electron transport, and thermal diffusion in defect-free silica for temperatures up to 15,000K and pressures < 15GPa. In addition to the practical application of selecting an optimal laser for pre-initiation of large aperture optics, this work serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

Carr, C W; Bude, J D; Shen, N; Demange, P

2010-10-26

380

Iodine laser pumped with light from a shock front produced by explosive charge detonation  

NASA Astrophysics Data System (ADS)

The paper presents results of experimental research undertaken during 1965-1966 which concerned a pulsed photodissociation iodine laser using CF3I and C3F7I molecules pumped with light from a shock front produced by explosive charge detonation. These lasers are shown to feature a unique combination of the high energy and the high power of the radiation pulse. Two types of lasers were investigated, in one of which the active medium was pumped with light from the shock front in xenon, while in the other the shock wave propagated through a mixture of the active medium with a rare gas. The energy characteristics of the second type of laser substantially surpassed those of the first type of laser.

Arzhanov, V. P.; Borovich, B. L.; Zuev, V. S.; Kazanskii, V. M.; Katulin, V. A.; Kirillov, G. A.; Kormer, S. B.; Kuratov, Iu. V.; Kuriapin, A. I.; Nosach, O. Iu.

1992-02-01

381

Deflagration-to-detonation transition in granular HMX  

NASA Technical Reports Server (NTRS)

Granular HMX of three degrees of fineness was packed into heavy-walled steel tubes closed at both ends. Ignition was obtained at one end using an intimate mixture of finely divided titanium and boron as an igniter that produced heat with little gas. The distance to detonation was determined by examination of the resulting tube fragments. By inserting tightly-fitted neoprene diaphragms periodically into the HMX column, it was shown that the role of convective combustion was limited to the initial stage of the deflagration to detonation (DDT) process. Experiments in which various combinations of two of the three types of HMX were loaded into the same tube showed that heating by adiabatic shear of explosive grains was an essential factor in the final buildup to detonation. A description of the DDT process is developed in which conductive burning is followed in turn by convective burning, bed collapse with plug formation, onset of accelerated burning at the front of the plug through heating by intercrystalline friction and adiabatic shear, and intense shock formation resulting in high-order detonation.

Campbell, A. W.

1980-01-01

382

Detonation and combustion of explosives: A selected bibliography  

SciTech Connect

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

Dobratz, B. [comp.

1998-08-01

383

Numerical Modeling of Pulse Detonation Rocket Engine Gasdynamics And Performance  

NASA Technical Reports Server (NTRS)

Pulse detonation rocket engines (PDREs) offer potential performance improvements over conventional designs, but represent a challenging modeling task. A quasi-1-D, finite-rate chemistry computational fluid dynamics model for PDREs is described and implemented. Four different PDRE geometries are evaluated in this work: a baseline detonation tube, a detonation tube with a straight extension, and a detonation tube with two types of converging-diverging (C-D) nozzles. The effect of extension length and C-D nozzle area ratio on the single-shot gasdynamics and performance of a PDRE is studied over a wide range of blowdown pressure ratios (1-1000). The results indicate that a C-D nozzle is generally more effective than a straight extension in improving PDRE performance, particularly at higher pressure ratios. Additionally, the results show that the blowdown process of the C-D nozzle systems could be beneficially cut off well before the pressure at the end-wall reaches the ambient value. The performance results are also compared to a steady-state rocket system using similar modeling assumptions.

Morris, Christopher I.

2004-01-01

384

Formic acid as a detonation product. [CHNO explosives  

SciTech Connect

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

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

1986-06-13

385

The Ghost Fluid Method for deflagration and detonation discontinuities  

E-print Network

The Ghost Fluid Method for deflagration and detonation discontinuities Ronald P. Fedkiw \\Lambda to suffer from large spurious oscillations in [13]. In [5], a new Ghost Fluid Method (GFM) was shown Kutta methods, are difficult to implement for these schemes. The Ghost Fluid Method (GFM) [5] avoids

Aslam, Tariq

386

The Ghost Fluid Method for de agration and detonation discontinuities  

E-print Network

The Ghost Fluid Method for de agration and detonation discontinuities Ronald P. Fedkiw Tariq Aslam large spurious oscillations in 13 . In 5 , a new Ghost Fluid Method GFM was shown to remove for these schemes. The Ghost Fluid Method GFM 5 avoids the oscillations at multimate- rial interfaces without

Aslam, Tariq

387

The Ghost Fluid Method for de agration and detonation discontinuities  

E-print Network

The Ghost Fluid Method for de agration and detonation discontinuities Ronald P. Fedkiw #3; Tariq to su#11;er from large spurious oscillations in [15]. In [7], a new Ghost Fluid Method (GFMÃ?cult to implement for these schemes. The Ghost Fluid Method (GFM) [7] avoids the oscillations at multimate- rial

Soatto, Stefano

388

Detonation Calorimeter and Results Obtained with Pentaerythritol Tetranitrate (PETN)  

Microsoft Academic Search

A bomb calorimeter for measuring the heat of detonation of 25 g charges of high explosive is described. A complete calorimetric measurement can be made in 1 h with a precision of 0.3%. Calorimetric measurements and analysis for PETN are described. The data are interpreted with the aid of thermodynamic and hydrodynamic computer calculations. For unconfined or lightly confined charges,

Donald L. Ornellas; John H. Carpenter; Stuart R. Gunn

1966-01-01

389

The Nuclear Detonation Detection System on the GPS satellites  

SciTech Connect

This article begins with a historical perspective of satellite usage in monitoring nuclear detonations. Current capabilities of the 24 GPS satellites in detecting the light, gamma rays, x-rays and neutrons from a nuclear explosion are described. In particular, an optical radiometer developed at Sandia National Laboratories is characterized. Operational information and calibration procedures are emphasized.

Higbie, P.R. [Los Alamos National Lab., NM (United States); Blocker, N.K. [Sandia National Labs., Albuquerque, NM (United States)

1993-07-27

390

The effect of detonation curvature on cylindrical wall motion  

SciTech Connect

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

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

1991-06-04

391

Detonation equation of state at LLNL, 1995. Revision 3  

SciTech Connect

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

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

1996-02-01

392

State of Detonation Stability Theory and Its Application to Propulsion  

E-print Network

rocket motor combustion, advanced level set methods, and computational modeling of reactive flow. HeState of Detonation Stability Theory and Its Application to Propulsion D. Scott Stewart University theory and discuss its implications for propulsion. The emphasis of the review is on the exact

Kasimov, Aslan

393

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

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

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

394

Dimensional analysis of impulse loading resulting from detonation  

E-print Network

. Design/methodology/approach ­ In the present work, a critical assessment is carried out of some for the problem of impulse loading experienced by target structures (e.g. vehicle hull) due to detonation products takes place). Once the dimensional analysis is reformulated, a variety of experimental results

Grujicic, Mica

395

Model for Shock Wave Chaos  

NASA Astrophysics Data System (ADS)

We propose the following model equation, ut+1/2(u2-uus)x=f(x,us) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x=0 for any t?0. Here, us(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.

Kasimov, Aslan R.; Faria, Luiz M.; Rosales, Rodolfo R.

2013-03-01

396

Galloping instability of viscous shock waves  

Microsoft Academic Search

Motivated by physical and numerical observations of time oscillatory ``galloping'', ``spinning'', and ``cellular'' instabilities of detonation waves, we study Poincar\\\\'e--Hopf bifurcation of traveling-wave solutions of viscous conservation laws. The main difficulty is the absence of a spectral gap between oscillatory modes and essential spectrum, preventing standard reduction to a finite-dimensional center manifold. We overcome this by direct Lyapunov--Schmidt reduction, using

Benjamin Texier; Kevin Zumbrun

2006-01-01

397

The Initiation and Propagation of Helium Detonations in White Dwarf Envelopes  

E-print Network

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

Shen, Ken J

2014-01-01

398

Method for attenuating seismic shock from detonating explosive in an in situ oil shale retort  

DOEpatents

In situ oil shale retorts are formed in formation containing oil shale by excavating at least one void in each retort site. Explosive is placed in a remaining portion of unfragmented formation within each retort site adjacent such a void, and such explosive is detonated in a single round for explosively expanding formation within the retort site toward such a void for forming a fragmented permeable mass of formation particles containing oil shale in each retort. This produces a large explosion which generates seismic shock waves traveling outwardly from the blast site through the underground formation. Sensitive equipment which could be damaged by seismic shock traveling to it straight through unfragmented formation is shielded from such an explosion by placing such equipment in the shadow of a fragmented mass in an in situ retort formed prior to the explosion. The fragmented mass attenuates the velocity and magnitude of seismic shock waves traveling toward such sensitive equipment prior to the shock wave reaching the vicinity of such equipment.

Studebaker, Irving G. (Grand Junction, CO); Hefelfinger, Richard (Grand Junction, CO)

1980-01-01

399

A review of direct numerical simulations of astrophysical detonations and their implications  

NASA Astrophysics Data System (ADS)

Multi-dimensional direct numerical simulations (DNS) of astrophysical detonations in degenerate matter have revealed that the nuclear burning is typically characterized by cellular structure caused by transverse instabilities in the detonation front. Type Ia supernova modelers often use onedimensional DNS of detonations as inputs or constraints for their whole star simulations.While these one-dimensional studies are useful tools, the true nature of the detonation is multi-dimensional. The multi-dimensional structure of the burning influences the speed, stability, and the composition of the detonation and its burning products, and therefore, could have an impact on the spectra of Type Ia supernovae. Considerable effort has been expended modeling Type Ia supernovae at densities above 1×107 g·cm-3 where the complexities of turbulent burning dominate the flame propagation. However, most full star models turn the nuclear burning schemes off when the density falls below 1×107 g·cm-3 and distributed burning begins. The deflagration to detonation transition (DDT) is believed to occur at just these densities and consequently they are the densities important for studying the properties of the subsequent detonation. This work will review the status of DNS studies of detonations and their possible implications for Type Ia supernova models. It will cover the development of Detonation theory from the first simple Chapman-Jouguet (CJ) detonation models to the current models based on the time-dependent, compressible, reactive flow Euler equations of fluid dynamics.

Parete-Koon, Suzanne T.; Smith, Christopher R.; Papatheodore, Thomas L.; Bronson Messer, O. E.

2013-04-01

400

A morphological investigation of soot produced by the detonation of munitions.  

PubMed

The morphology of three different detonation soot samples along with other common soot materials such as carbon black, diesel soot and chimney soot was studied by elemental and proximate analysis, X-ray diffraction and electron microscopy. The goal of this study was to better define the morphology of the detonation soot in order to better assess the interactions of this type of soot with explosive residues. The detonation soot samples were obtained by the detonation of artillery 155mm projectiles filled with either pure TNT (2,4,6-trinitrotoluene) or composition B, a military explosive based on a mixture of TNT and RDX (trimethylentrinitramine). The carbon content of the soot samples varied considerably depending on the feedstock composition. Detonation soot contains less carbon and more nitrogen than the other carbonaceous samples studied, due to the molecular structure of the energetic materials detonated such as TNT and RDX. The ash concentration was higher for detonation soot samples due to the high metal content coming from the projectiles shell and to the soil contamination which occurred during the detonation. By X-ray diffraction, diamond and graphite were found to be the major crystalline carbon forms in the detonation soot. Two electron microscopy techniques were used in this study to visualise the primary particles and to try to explain the formation mechanism of detonation soot samples. PMID:16674994

Pantea, Dana; Brochu, Sylvie; Thiboutot, Sonia; Ampleman, Guy; Scholz, Günter

2006-10-01

401

Study on Al-Si alloy-based nanocomposites with dispersed detonation nanodiamonds.  

PubMed

Al-Si alloy-based nanocomposites with dispersed detonation nanodiamonds are fabricated by a powder metallurgy method. Rapid-solidified Al-Si alloy powder and detonation nanodiamond of 1% by volume are mechanically mixed at 500 rpm for 4 h; the nanoadditives used above are as-synthesized and purified detonation nanodiamonds. The obtained Al-Si nanocomposite mixtures are consolidated at 773 K by vacuum-hot pressing. The microstructural observations indicate that the fabricated Al-Si nanocomposites have fine grain structures with dispersed eutectic Si particles and detonation nanodiamonds in the grains; structural changes in the dispersed nanodiamonds are not observed. The mechanical and friction properties of the fabricated Al-Si nanocomposites with dispersed detonation nanodiamonds are investigated by carrying out indentation and friction measurements. It is observed that the dispersion of detonation nanodiamonds in the Al-Si alloy matrix improves its mechanical and friction properties. In particular, the dispersion of the purified detonation nanodiamond enhances the elastic modulus of the nanocomposite to a greater extent than that of the as-synthesized detonation nanodiamond with graphitic shell structure; in contrast, the use of the as-synthesized detonation nanodiamond reduces friction to a greater extent than the use of the purified detonation nanodiamond. PMID:20355493

Hanada, K; Sano, T

2010-04-01

402

A Mechanistic Study of Delayed Detonation in Impact Damaged Solid Rocket Propellant  

NASA Astrophysics Data System (ADS)

One method of hazard assessment for mass detonable solid rocket propellants consists of impacting right circular cylinders of propellant end-on into thick steel witness plates at varying impact velocities. A detonation that occurs within one shock traversal of the cylinder length is termed a prompt detonation or a shock-to-detonation transition (SDT). At lower velocities, some propellants detonate at times later than one shock transit, typically 1-5 shock transits. Because no mechanism for delayed detonation has been fully confirmed and accepted by the detonation physics community, these low-velocity detonations are referred to as unknown-to-detonation transitions (XDTs). A leading theory, however, is that prior to detonation mechanically induced damage sensitizes the material through the formation of internal porosity which provides new mechanical reaction initiation sites (hot spots) and enhanced internal burn surface. To study this phenomenology, we have developed the Coupled Damage and Reaction (CDAR) model, implemented it in the CTH shock physics code, and simulated propellant impact experiments. The CDAR model fully couples viscoelastic-viscoplastic deformation, tensile damage, porosity evolution, reaction initiation, and grain burning to model the increased reactivity of the propellant. In this paper, CDAR simulations of propellant damage in spall and Taylor impact tests are presented and compared to experiment. An XDT experiment is also simulated, and implications regarding damage mechanisms and hydrodynamic processes leading to XDT are discussed.

Matheson, E. R.; Rosenberg, J. T.

2002-07-01

403

A Review of Direct Numerical Simulations of Astrophysical Detonations and Their Implications  

SciTech Connect

Multi-dimensional direct numerical simulations (DNS) of astrophysical detonations in degenerate matter have revealed that the nuclear burning is typically characterized by cellular structure caused by transverse instabilities in the detonation front. Type Ia supernova modelers often use one- dimensional DNS of detonations as inputs or constraints for their whole star simulations. While these one-dimensional studies are useful tools, the true nature of the detonation is multi-dimensional. The multi-dimensional structure of the burning influences the speed, stability, and the composition of the detonation and its burning products, and therefore, could have an impact on the spectra of Type Ia supernovae. Considerable effort has been expended modeling Type Ia supernovae at densities above 1 107 g cm 3 where the complexities of turbulent burning dominate the flame propagation. However, most full star models turn the nuclear burning schemes off when the density falls below 1 107 g cm 3 and distributed burning begins. The deflagration to detonation transition (DDT) is believed to occur at just these densities and consequently they are the densities important for studying the properties of the subsequent detonation. This work will review the status of DNS studies of detonations and their possible implications for Type Ia supernova models. It will cover the development of Detonation theory from the first simple Chapman-Jouguet (CJ) detonation models to the current models based on the time-dependent, compressible, reactive flow Euler equations of fluid dynamics.

Parete-Koon, Suzanne T [ORNL; Messer, Bronson [ORNL; Smith, Chris R [ORNL; Papatheodore, Thomas L [ORNL

2013-01-01

404

Sensitization of two-dimensional detonations in nitromethane by glass microballoons  

NASA Astrophysics Data System (ADS)

Experimental results are reported on charge diameter effect and critical detonation diameter of nitromethane (NM) gelled by 4 wt.% of PMMA and sensitized by thin-walled (1 ? m) monosize glass microballoons (GMB) of 47 ? m or 102 ? m size at a constant mass fraction of glass (1%) in the mixture. The dependence of the detonation velocity on the detonation shock-front total curvature at the explosive charge axis is presented for steel and PVC detonation tubes of various inner diameters. The predictive ability of the quasi-one-dimensional hydrodynamic model of detonation-reaction zone in GMB-sensitized NM is improved by a better description of the hot spot growth stage. Dependencies of detonation velocity in NM sensitized by different GMBs on the charge diameter are calculated using available data on NM regression rate at detonation pressures and a reasonable agreement with experimental data is obtained. The effect of the confinement on the charge diameter effect as well as the dependence of the normal detonation velocity on the total detonation shock front curvature at the charge axis is also predicted by the model. However, there are still some difficulties in reproducing the experimental linear correlation between the critical detonation diameter of GMB-sensitized nitromethane and its reciprocal specific surface area.

Bouton, E.; Khasainov, B. A.; Presles, H. N.; Vidal, P.; Ermolaev, B. S.

405

Verification of 2-D Detonation Shock Dynamics in conjunction with Los Alamos Lagrangian hydrocode  

SciTech Connect

As the latest version of the fast-tube Detonation Shock Dynamics (DSD) solver is linked with the Los Alamos Lagrangian hydrocode, verification problems from a 2006 DSD report (LA-14277 [1]) have been duplicated with some of the verification criteria changed to more quantitative ones. The observed error convergence is as good as or better than reported in [1], quite possibly due to the careful treatment of floating point numbers to ensure that their precision level is maintained throughout the code. This report duplicates the three sample verification problems in LA-14277 [1] using the Los Alamos ASC Lagrangian hydrocode (FLAG), official release of 3.2 Alpha6 with a few modifications. This version of FLAG is linked with the latest fast-tube Detonation Shock Dynamics (DSD) version beta 2 solver released in 2011 as part of the LanlDSD software product [2]. New verification criteria are used for the arcwave problem where two specific locations are chosen for burn arrival time comparison. For this report FLAG's internal driver code prepares the distance function ({Psi}) and material ID fields from its hydro setup, instead of the stand-alone driver that is being utilized by the other LANL hydrocodes currently interfaced to LanlDSD. As it is implemented in version 3.2 Alpha6, the {Psi} and material ID fields and other parameters are passed from FLAG to the DSD solver directly, and the burn table is directly passed back to FLAG as part of the calling arguments. The burn-front arrival time 'exact' solutions, mentioned in the sequel for the rate-stick and 'arc-wave' problems, are computed using a pair of special-purpose Fortran codes provided by Aslam [3]. In each case an ansatz for the form of the solution is made in which the radius from the detonator center point is used as the independent space coordinate. This leads to a simplified, problem-specific, 1D form of the governing equation. This equation is solved using 2nd-order spatial differencing and the forward Euler method on a very fine temporal and geometric mesh. The boundary conditions are handled exactly at the correct location, with second order accuracy. Care has been taken to ensure that this solution is fully converged. Most other technical details are omitted here as they are comprehensively discussed in [1].

Aida, Toru [Los Alamos National Laboratory; Walter, John W. [Los Alamos National Laboratory; Aslam, Tariq D. [Los Alamos National Laboratory; Short, Mark [Los Alamos National Laboratory

2013-01-29

406

Pediatric neurological disorder and present nuclear detonation: a hot issue.  

PubMed

It is no doubt for the health effect of the radiation from the nuclear detonation from the destroyed nuclear power plant. Due to the present crisis in Japan, the public health concern on this issue should be raised. In pediatric neurology, there are some interesting reports on pediatric neurological disorder and its relationship to leaked radiation. In this specific brief article, the author hereby discusses on the nuclear detonation and pediatric neurological disorder. Although there are some reports on the increased incidence of some pediatric neurological malignancies and congenital neurological anomalies there is no confirmed evidence. Effect on cognitive function is still controversial. The induction of abnormal electroencephalography is also mentioned. The observation on the effect of present crisis in pediatric neurology can provide more information and help better understand this topic. PMID:22670268

Wiwanitkit, Viroj

2011-12-01

407

Engineering models of deflagration-to-detonation transition  

SciTech Connect

For the past two years, Los Alamos has supported research into the deflagration-to-detonation transition (DDT) in damaged energetic materials as part of the explosives safety program. This program supported both a theory/modeling group and an experimentation group. The goal of the theory/modeling group was to examine the various modeling structures (one-phase models, two-phase models, etc.) and select from these a structure suitable to model accidental initiation of detonation in damaged explosives. The experimental data on low-velocity piston supported DDT in granular explosive was to serve as a test bed to help in the selection process. Three theoretical models have been examined in the course of this study: (1) the Baer-Nunziato (BN) model, (2) the Stewart-Prasad-Asay (SPA) model and (3) the Bdzil-Kapila-Stewart model. Here we describe these models, discuss their properties, and compare their features.

Bdzil, J.B.; Son, S.F.

1995-07-01

408

Performance Impact of Deflagration to Detonation Transition Enhancing Obstacles  

NASA Technical Reports Server (NTRS)

A sub-model is developed to account for the drag and heat transfer enhancement resulting from deflagration-to-detonation (DDT) inducing obstacles commonly used in pulse detonation engines (PDE). The sub-model is incorporated as a source term in a time-accurate, quasi-onedimensional, CFD-based PDE simulation. The simulation and sub-model are then validated through comparison with a particular experiment in which limited DDT obstacle parameters were varied. The simulation is then used to examine the relative contributions from drag and heat transfer to the reduced thrust which is observed. It is found that heat transfer is far more significant than aerodynamic drag in this particular experiment.

Paxson, Daniel E.; Schauer, Frederick; Hopper, David

2012-01-01

409

Numerical Simulation of Anti-tank Mine Detonations  

NASA Astrophysics Data System (ADS)

In order to determine the loads on mine-clearing devices generated by detonations of anti-tank mines, knowledge about the incident impulse and pressure generated in the air are needed. Dependent factors include the mine's depth of burial and the properties of the soil. Numerical simulations were performed with a multi-material Euler processor to determine incident impulses and pressure histories from detonations of fully buried, flushed and surface anti-tank mines for dry porous sand and saturated clay. The simulations showed that the maximum incident impulse in air, at stand off distance below 1 m, increases for both flushed and buried mines compared to a surface mine. Additionally, a concentration in the vertical direction of the maximum impulse was found for the buried mine. For buried mines it was found that the incident maximum pressure and impulse straight above the mines were significantly affected by the soil material properties.

Laine, Leo; Ranestad, Øyvind; Sandvik, Andreas; Snekkevik, Asbjørn

2002-07-01

410

Detonating Failed Deflagration Model of Thermonuclear Supernovae I. Explosion Dynamics  

E-print Network

We present a detonating failed deflagration model of Type Ia supernovae. In this model, the thermonuclear explosion of a massive white dwarf follows an off-center deflagration. We conduct a survey of asymmetric ignition configurations initiated at various distances from the stellar center. In all cases studied, we find that only a small amount of stellar fuel is consumed during deflagration phase, no explosion is obtained, and the released energy is mostly wasted on expanding the progenitor. Products of the failed deflagration quickly reach the stellar surface, polluting and strongly disturbing it. These disturbances eventually evolve into small and isolated shock-dominated regions which are rich in fuel. We consider these regions as seeds capable of forming self-sustained detonations that, ultimately, result in the thermonuclear supernova explosion. Preliminary nucleosynthesis results indicate the model supernova ejecta are typically composed of about 0.1-0.25 Msun of silicon group elements, 0.9-1.2 Msun of ...

Plewa, T

2006-01-01

411

Dependence of the Observed Properties of Type Ia Supernovae on the Mass of the Progenitor White Dwarf in the Gravitationally Confined Detonation Model  

NASA Astrophysics Data System (ADS)

We investigate the dependence of the observed properties of Type Ia supernovae on the mass MWD of the white dwarf star in the single degenerate model. We find that, within the gravitationally confined detonation (GCD) model and the treatment we use for buoyancy-driven turbulent nuclear burning, the outcome of the explosion is highly sensitive to MWD. Specifically, we find that the nuclear energy released during the deflagration phase, and therefore the amount by which the white dwarf expands prior to initiation of the detonation wave, increase rapidly as MWD increases. Consequently, the amount of radioactive nickel produced, and thus the peak luminosity of the supernova, decrease rapidly as MWD increases. We find that, as a result, ignition at a single point (which is favored by simulations of the prior smoldering phase) and a variation in MWD of as little as ~ 2% can produce the observed range of peak luminosities of normal Type Ia supernovae.

Lamb, Don Q.; Jordan, George C; Wuyts, Eva; Jumper, Kevin A.; Fisher, Robert

2014-08-01

412

One-dimensional overdriven detonations with branched-chain kinetics  

NASA Astrophysics Data System (ADS)

The dynamics of time-dependent, planar propagation of gaseous detonations is addressed on the basis of a three-step chemistry model that describes branched-chain processes. Relevant nondimensional parameters are the ratio of the heat release to the thermal enthalpy at the Neumann state, the nondimensional activation energies for the initiation and branching steps, the ratio of the branching time to the initiation time and the ratio of the branching time to the recombination time. The limit of strong overdrive is considered, in which pressure remains constant downstream from the leading shock in the first approximation, and the ratio of specific heats ? is taken to be near unity. A two-term expansion in the strong overdrive factor is introduced, and an integral equation is derived describing the nonlinear dynamics and exhibiting a bifurcation parameter, the reciprocal of the product of (?-1), the nondimensional heat release and the nondimensional branching activation energy, with an acoustic correction. A stability analysis shows that, depending on values of the parameters, either the mode of lowest frequency or a mode of higher frequency may be most unstable. Numerical integrations exhibit different conditions under which oscillations die, low-frequency oscillations prevail, high-frequency oscillations prevail, highly nonlinear oscillations persist, or detonation failure occurs. This type of parametric analysis is feasible because of the relative simplicity of the model, which still is more realistic than a one-step, Arrhenius chemical approximation. In particular, by addressing the limit of slow radical recombination compared with branching, explicit results are derived for the critical value of the bifurcation parameter, involving the ratio of the recombination time to the induction time. The results help to clarify the general nature of one-dimensional detonation instability and provide simplifications that can be employed in efficiently relating gaseous detonation behavior to the true underlying chemistry.

Sánchez, Antonio L.; Carretero, Manuel; Clavin, Paul; Williams, Forman A.

2001-03-01

413

High speed radiometric measurements of IED detonation fireballs  

NASA Astrophysics Data System (ADS)

Continuum emission is predominant in fireball spectral phenomena and in some demonstrated cases, fine detail in the temporal evolution of infrared spectral emissions can be used to estimate size and chemical composition of the device. Recent work indicates that a few narrow radiometric bands may reveal forensic information needed for the explosive discrimination and classification problem, representing an essential step in moving from "laboratory" measurements to a rugged, fieldable system. To explore phenomena not observable in previous experiments, a high speed (10?s resolution) radiometer with four channels spanning the infrared spectrum observed the detonation of nine home made explosive (HME) devices in the < 100lb class. Radiometric measurements indicate that the detonation fireball is well approximated as a single temperature blackbody at early time (0 < t <~ 3ms). The effective radius obtained from absolute intensity indicates fireball growth at supersonic velocity during this time. Peak fireball temperatures during this initial detonation range between 3000.3500K. The initial temperature decay with time (t <~ 10ms) can be described by a simple phenomenological model based on radiative cooling. After this rapid decay, temperature exhibits a small, steady increase with time (10 <~ t <~ 50ms) and peaking somewhere between 1000.1500K-likely the result of post-detonation combustion-before subsequent cooling back to ambient conditions . Radius derived from radiometric measurements can be described well (R2 > 0.98) using blast model functional forms, suggesting that energy release could be estimated from single-pixel radiometric detectors. Comparison of radiometer-derived fireball size with FLIR infrared imagery indicate the Planckian intensity size estimates are about a factor of two smaller than the physical extent of the fireball.

Spidell, Matthew T.; Gordon, J. Motos; Pitz, Jeremey; Gross, Kevin C.; Perram, Glen P.

2010-04-01

414

Pulse Detonation Rocket Engine Research at NASA Marshall  

NASA Technical Reports Server (NTRS)

Pulse detonation rocket engines (PDREs) offer potential performance improvements over conventional designs, but represent a challenging modeling task. A quasi 1-D, finite-rate chemistry CFD model for a PDRE is described and implemented. A parametric study of the effect of blowdown pressure ratio on the performance of an optimized, fixed PDRE nozzle configuration is reported. The results are compared to a steady-state rocket system using similar modeling assumptions.

Morris, Christopher I.

2003-01-01

415

Quasi-One-Dimensional Modeling of Pulse Detonation Rocket Engines  

NASA Technical Reports Server (NTRS)

Pulse detonation rocket engines (PDREs) offer potential performance improvements over conventional designs, but represent a challenging modeling task. A quasi 1-D, finite-rate chemistry CFD model for a PDRE & described and implemented. A parametric study of the effect of blowdown pressure ratio on the performance of an optimized, fixed PDRE nozzle configuration is reported. The results are compared to a steady-state rocket system using similar modeling assumptions.

Morris, Christopher I.

2003-01-01

416

Method for fabricating non-detonable explosive simulants  

DOEpatents

A simulator is disclosed 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.

1995-05-09

417

Method for fabricating non-detonable explosive simulants  

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)

1995-01-01

418

DDT Characteristics of Laser Driven Exploding Bridgewire Detonators  

NASA Astrophysics Data System (ADS)

The initiation and performance characteristics of Laser Exploding Bridgewire (LEBW) detonators loaded with CL-20, CP and BNCP were examined. LEBW devices, in name, as well as in function, exhibit similarities to their electrically driven counterparts with the exception that the means for energy deposition into the driving metal media results from photon absorption instead of electrical joule heating. CP and BNCP were chosen due to their well-known propensity to rapidly undergo a deflagration-to-detonation transition (DDT) and CL-20 was chosen to explore its utility as a DDT explosive. The explosive loading within the LEBW detonators were similar in nature to traditional EBW devices with regard to %TMD loading of the initial increment as well as quantity of energetic materials. Comparisons of the energy fluences required for initiation of the explosives will be discussed. Additionally, streak camera measurements will be reviewed that were conducted at what would be considered ``hard-fire'' fluence levels as well as conditions closer to the mean firing fluence levels of initiation.

Welle, Eric

2005-07-01

419

The deflagration-to-detonation transition in granular HMX  

SciTech Connect

The transition from deflagration to detonation in porous beds of explosive and propellant has received considerable attention both experimentally and theoretically. In many cases, the use of a hot-gas-producing igniter complicates the interpretation and subsequent modeling of experiments because considerable effort is required to account for the effect of the igniter gases on the granular bed. Hot-wire ignition is less intrusive; however, the ignition front is not planar. Thus the early events in these experiments cannot be approximated as one-dimensional. We have studied the deflagration-to-detonation behavior of granular HMX confined in steel tubes with x-radiography, light emission, stress gauges, and various pin techniques. Simplification and consistency of results were obtained by igniting the HMX with a piston (initially at rest and in contact with the HMX) driven into the bed. A gasless igniter is used to stare the burning of the piston propellant (low-density HMX) providing the piston with a smooth initial motion. Analysis of the data gives a detailed picture of the DDT process under these conditions. The qualitative and quantitative experimental results show the transition from the burning to detonation is discontinuous. The results are discussed in terms of a descriptive model.

McAfee, J.M.; Asay, B.; Campbell, A.W.; Ramsay, J.B.

1991-01-01

420

Equation of state, initiation, and detonation of pure ammonium nitrate  

NASA Astrophysics Data System (ADS)

Ammonium nitrate (AN) is a widely used fertilizer and mining explosive throughout the world. One of the more common explosives using AN is called ANFO, a mixture of AN prills and fuel oil in a 94:6 ratio by weight. The AN prills are specially made to absorb the fuel oil, forming a mixture that reacts under shock loading through a diffusion-controlled process, resulting in a non-ideal explosive with detonation velocities around 4 km/s. While there are a number of studies on ANFO, there are only a few studies relating to the equation of state (EOS) and detonation properties of pure AN - resulting mainly from studies of accidents that have occurred during transportation of large quantities of AN. We present the results of a series of gas gun-driven plate impact experiments on pressed AN ranging in density from 1.72 to 0.9 g/cm^3. Several of the high density experiments were performed in front surface impact geometry, in which pressed AN disks were built into the projectile front and impacted onto LiF windows. Additional experiments at low density have been done in ``half cell'' multiple magnetic gauge gun experiments. From this work a complete unreacted EOS has been developed, as well as some initiation and detonation information. Additional high pressure x-ray diffraction experiments in diamond anvil cells have provided a static isotherm for AN.

Robbins, D. L.; Sheffield, S. A.; Dattelbaum, D. M.; Velisavljevic, N.; Stahl, D. B.

2009-06-01

421

High and low velocity detonation in a highly insensitive explosive  

NASA Astrophysics Data System (ADS)

Low-velocity detonation (LVD) in a solid explosive from input shocks below the threshold for high-velocity detonation (HVD) had been previously reported for PBXN-109 in two gap tests with sample diameters of 36.5 and 73.0 mm. Similar phenomenon has now been observed for the highly insensitive PBXIH-140, whose critical diameter of ~100 mm required an even larger gap test with a sample diameter of 178 mm. When just exceeding the critical gap for HVD, LVD propagated at similar velocities as in PBXN-109 and would punch clean holes in a witness plate like HVD. For somewhat greater gaps, there was enough shock reaction to drive LVD at constant but reduced velocities as the input shock decreased to ~ ½ of critical. With a different formulation now exhibiting LVD, it may be more prevalent than previously realized. It is speculated to occur in various confinements when small percentages of easily detonable ingredients fail to initiate the remainder of less shock sensitive ingredients.

Sandusky, H. W.; Hayden, H. F.

2014-05-01

422

Detonation Initiation by Gradient Mechanism in Propane--Oxygen and Propane--Air Mixtures  

NASA Astrophysics Data System (ADS)

An experimental study of detonation initiation by high--voltage nanosecond gas discharge has been performed in smooth detonation tubes. A gradient mechanism was used to initiate detonations in stoichiometric propane--oxygen mixtures with different nitrogen dilution and in propane--air mixtures. Initial pressures from 0.2 to 1bar have been tested. Detonation was formed within 4 transverse tube sizes at initial pressures higher than 0.2 bar for the propane--oxygen mixture and higher than 0.8 bar for the diluted mixture with 40% of nitrogen. The discharge energy inputs were 0.2---0.3 J. The gradient mechanism of detonation formation similar to the one suggested by Zeldovich has been shown to be the governing process. For the mixture with air, a detonation tube with an annular discharge chamber has been designed and tested.

Rakitin, Aleksandr; Popov, Ilya; Starikovskiy, Andrey

2011-11-01

423

Experimental research on the rotating detonation in gaseous fuels–oxygen mixtures  

Microsoft Academic Search

An experimental study on rotating detonation is presented in this paper. The study was focused on the possibility of using\\u000a rotating detonation in a rocket engine. The research was divided into two parts: the first part was devoted to obtaining the\\u000a initiation of rotating detonation in fuel–oxygen mixture; the second was aimed at determination of the range of propagation\\u000a stability

J. Kindracki; P. Wolanski; Z. Gut

2011-01-01

424

Excess transit time as a function of burst current in an exploding bridgewire detonator  

SciTech Connect

Transit time, the time from bridgewire burst until breakout of detonation from the output pellet of an exploding bridgewire detonator, was measured as a function of burst current. From this data, in conjunction with known equations for run distance versus pressure, unreacted explosive Hugoniots, and detonation properties of the initial pressing pellet, the run distance in the initial pressing explosive pellet and shock pressure from the exploding bridgewire were determined, both as a function of burst current.

Cooper, P.W.; Owenby, R.N.; Stofleth, J.H.

1990-01-01

425

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

Microsoft Academic Search

Summary  A new model to predict the non-ideal detonation behaviour of commercial explosives in rock blasting is presented. The model\\u000a combines the slightly divergent flow theory, polytropic equation of state, simple pressure-dependent rate law and statistical\\u000a expressions to model the effect of confinement on detonation. The model has been designated as DeNE, an acronym for the Detonics\\u000a of Non-ideal Explosives. It

S. Esen

2008-01-01

426

a Simple Line Wave Generator Using Commercial Explosives  

NASA Astrophysics Data System (ADS)

We present a simple and inexpensive explosive line wave generator which has been designed using commercial sheet explosive and plane wave lens concepts. The line wave generator is constructed using PETN- and RDX-based sheet explosive for the slow and fast components, respectively, and permits the creation of any desired line width. A series of experiments were performed on a 100-mm design, measuring the detonation arrival time at the output of the generator using a streak camera. An iterative technique was used to adjust the line wave generator's slow and fast components, so as to minimize the arrival time deviation. Preliminary tests achieved a wavefront simultaneity of 100 ns with a 7.0 mm/?s detonation wave. Designs, test results, and concepts for improvements are discussed.

Morris, John S.; Jackson, Scott I.; Hill, Larry G.

2009-12-01

427

American Institute of Aeronautics and Astronautics The Direct Simulation of Detonations  

E-print Network

transient, multidimensional C++ program has led to the current investigation into complex explosive mechanisms. A. Brief History The history of detonation includes a small number of important scientific

428

Measurement and calculation of shock wave attenuation in a rough duct  

NASA Astrophysics Data System (ADS)

Shock wave attenuation a duct with rough walls was calculated using an approximate method and measured experimentally in a systematic manner, which made it possible to determine impulse losses in shock waves by comparing the analytical and experimental data. Expressions relating the loss coefficient to the regular surface roughness were then used for calculating the rate of gas detonation in ducts with rough walls.

Gel'Fand, B. E.; Frolov, S. M.; Medvedev, S. P.

1990-06-01

429

Alfvén Waves Generated by Expanding Plasmas in the Laboratory and in Space  

Microsoft Academic Search

There are many situations, which occur in space (coronal mass ejections, supernovas), or are man-made (upper atmospheric detonations) in which a dense plasma expands into a background magnetized plasma, that can support Alfvén waves. The LArge Plasma Device (LAPD) is a machine, at UCLA, in which Alfvén waves propagation in homogeneous and inhomogeneous plasmas has been studied. These will be

W. Gekelman; M. Vanzeeland; S. Vincena; P. Pribyl

2002-01-01

430

A STUDY OF THE LIQUEFACTION SHOCK WAVE STRUCTURE  

E-print Network

structure is governed by differences in the time scales associated with various relaxation mechanisms and phase­change mechanisms and their coupling to the macroscopic flow (3,4). In this paper, we present. It appears that instability mechanisms similar to the ones found in ZND detonation waves are responsible

New York at Stoney Brook, State University of

431

Free-surface velocity measurements of plates driven by reacting and detonating RX-03-BB and PBX-0404  

SciTech Connect

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. The free surface velocity of the plates were measured with a Fabry-Perot velocimeter. Excellent experimental free-surface velocity histories have been obtained. Calculations of this history employing beta-burn and nucleation and growth high explosives models are in good agreement with fully detonating experiments. For reacting RX-03-BB, adjustments in the parameter are needed. The experimental technique gives records whose agreement with calculation is sensitive to the model and is therefore a good way of testing new high explosive models. Also, this method allows one to infer information about the reaction zone length.

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

1981-07-13

432

EVALUATING THE USE OF SNOW-COVERED RANGES TO ESTIMATE THE EXPLOSIVES RESIDUES THAT RESULT FROM DETONATION OF ARMY MUNITIONS  

EPA Science Inventory

Estimating the amounts of residues remaining after munitions detonate is complicated by the presence of residues from previous detonations and the difficulty in easily obtaining adequately sized samples to overcome spatial heterogeneity in residue deposition. This study was cond...

433

The Erpenbeck high frequency instability theorem for ZND detonations  

E-print Network

The rigorous study of spectral stability for strong detonations was begun by J.J. Erpenbeck in [Er1]. Working with the Zeldovitch-von Neumann-D\\"oring (ZND) model, which assumes a finite reaction rate but ignores effects like viscosity corresponding to second order derivatives, he used a normal mode analysis to define a stability function $V(\\tau,\\eps)$ whose zeros in $\\Re \\tau>0$ correspond to multidimensional perturbations of a steady detonation profile that grow exponentially in time. Later in a remarkable paper [Er3] he provided strong evidence, by a combination of formal and rigorous arguments, that for certain classes of steady ZND profiles, unstable zeros of $V$ exist for perturbations of sufficiently large transverse wavenumber $\\eps$, even when the von Neumann shock, regarded as a gas dynamical shock, is uniformly stable in the sense defined (nearly twenty years later) by Majda. In spite of a great deal of later numerical work devoted to computing the zeros of $V(\\tau,\\eps)$, the paper \\cite{Er3} remains the only work we know of that presents a detailed and convincing theoretical argument for detecting them. The analysis in [Er3] points the way toward, but does not constitute, a mathematical proof that such unstable zeros exist. In this paper we identify the mathematical issues left unresolved in [Er3] and provide proofs, together with certain simplifications and extensions, of the main conclusions about stability and instability of detonations contained in that paper. The main mathematical problem, and our principal focus here, is to determine the precise asymptotic behavior as $\\eps\\to \\infty$ of solutions to a linear system of ODEs in $x$, depending on $\\eps$ and a complex frequency $\\tau$ as parameters, with turning points $x_*$ on the half-line $[0,\\infty)$.

Olivier Lafitte; Mark Williams; Kevin Zumbrun

2011-02-02

434

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

E-print Network

Pulsed Detonation Rockets Ramakanth Munipalli* , Vijaya Shankar HyPerComp, Inc., 31255, Cedar Valley Dr. As in the case of steady ejector based rockets, the pulsed detonation rockets (PDRs) may also be operated to enhance thrust and specific impulse at low speeds beyond that provided by conventional rockets, by adding

Texas at Arlington, University of

435

Impact of Dissociation and Sensible Heat Release on Pulse Detonation and Gas Turbine Engine Performance  

NASA Technical Reports Server (NTRS)

A thermodynamic cycle analysis of the effect of sensible heat release on the relative performance of pulse detonation and gas turbine engines is presented. Dissociation losses in the PDE (Pulse Detonation Engine) are found to cause a substantial decrease in engine performance parameters.

Povin