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Sample records for laser-supported detonation waves

  1. Laser-supported detonation waves and pulsed laser propulsion

    SciTech Connect

    Kare, J.T.

    1989-01-01

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

  2. Laser-supported detonation waves and pulsed laser propulsion

    SciTech Connect

    Kare, J. )

    1990-07-30

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

  3. Fundamental Properties of Non-equilibrium Laser-Supported Detonation Wave

    SciTech Connect

    Shiraishi, Hiroyuki

    2004-03-30

    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.

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

    SciTech Connect

    Shiraishi, Hiroyuki

    2006-05-02

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

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

    NASA Technical Reports Server (NTRS)

    Krech, Robert H.; Caledonia, George E.

    1990-01-01

    A pulsed high-flux source of nearly monoenergetic atomic oxygen was developed to perform accelerated erosion testing of spacecraft materials in a simulated low-earth orbit (LEO) environment. Molecular oxygen is introduced into an evacuated conical expansion nozzle at several atmospheres pressure through a pulsed molecular beam valve. A laser-induced breakdown is generated in the nozzle throat by a pulsed CO2 TEA laser. The resulting plasma is heated by the ensuing laser-supported detonation wave, and then it rapidly expands and cools. An atomic oxygen beam is generated with fluxes above 10 to the 18th atoms per pulse at 8 + or - 1.6 km/s with an ion content below 1 percent for LEO testing. Materials testing yielded the same surface oxygen enrichment in polyethylene samples as observed on the STS mission, and scanning electron micrographs of the irradiated polymer surfaces showed an erosion morphology similar to that obtained on low earth orbit.

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

    SciTech Connect

    Shimamura, Kohei; Kawamura, Koichi; Fukuda, Akio; Wang Bin; Yamaguchi, Toshikazu; Komurasaki, Kimiya; Hatai, Keigo; Fukui, Akihiro; Arakawa, Yoshihiro

    2011-04-15

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

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

    SciTech Connect

    Shiraishi, Hiroyuki

    2008-04-28

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

  8. Laser-Supported Detonation Concept as a Space Thruster

    SciTech Connect

    Fujiwara, Toshi; Miyasaka, Takeshi

    2004-03-30

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

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

    SciTech Connect

    Gan, Li Mousen, Cheng; Xiaokang, Li

    2014-03-15

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

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

    NASA Astrophysics Data System (ADS)

    Li, Gan; Cheng, Mousen; Li, Xiaokang

    2014-03-01

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

  11. Predicting propagation limits of laser-supported detonation by Hugoniot analysis

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  12. Detonation Wave Profile

    SciTech Connect

    Menikoff, Ralph

    2015-12-14

    The Zel’dovich-von Neumann-Doering (ZND) profile of a detonation wave is derived. Two basic assumptions are required: i. An equation of state (EOS) for a partly burned explosive; P(V, e, λ). ii. A burn rate for the reaction progress variable; d/dt λ = R(V, e, λ). For a steady planar detonation wave the reactive flow PDEs can be reduced to ODEs. The detonation wave profile can be determined from an ODE plus algebraic equations for points on the partly burned detonation loci with a specified wave speed. Furthermore, for the CJ detonation speed the end of the reaction zone is sonic. A solution to the reactive flow equations can be constructed with a rarefaction wave following the detonation wave profile. This corresponds to an underdriven detonation wave, and the rarefaction is know as a Taylor wave.

  13. Oblique detonation wave ramjet

    NASA Technical Reports Server (NTRS)

    Morrison, R. B.

    1980-01-01

    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.

  14. Light detonation wave in a cylindrical Z-pinch

    NASA Astrophysics Data System (ADS)

    Yusupaliev, U.; Sysoev, N. N.; Shuteev, S. A.; Elenskii, V. G.

    2015-09-01

    A secondary compression wave previously observed by other researchers in a cylindrical Z-pinch has been identified in this work as a light detonation wave. It appears on the inner surface of a discharge chamber under the action of the intense ultraviolet radiation from a plasma pinch at the stage of its maximum compression. The condition of the light detonation wave has been determined experimentally. The dependence of its Mach number on a generalized dimensionless variable has been determined taking into account the conservation laws for the light detonation wave including the pressure of the gas, expenses on the formation of the surface plasma, and the energy of ionization of the gas involved in the wave. An analogy with the laser-supported detonation wave created by intense laser radiation has been revealed. The indicated dependence is within the error of measurement in agreement with the experimental data for light detonation waves created by both methods.

  15. Photoionization in the Precursor of Laser Supported Detonation by Ultraviolet Radiation

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    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 μs and 0.3 μs, 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.

  16. Photoionization in the Precursor of Laser Supported Detonation by Ultraviolet Radiation

    SciTech Connect

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

    2011-11-10

    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.

  17. A reexamination of the laser supported combustion wave

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  18. Analytical study of laser-supported combustion waves in hydrogen

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    Laser supported combustion (LSC) waves are an important ingredient in the fluid mechanics of CW laser propulsion using a hydrogen propellant and 10.6 micron lasers. Therefore, a computer model has been constructed to solve the one-dimensional energy equation with constant pressure and area. Physical processes considered include convection, conduction, absorption of laser energy, radiation energy loss, and accurate properties of equilibrium hydrogen. Calculations for 1, 3, 10 and 30 atm were made for intensities of 10 to the 4th to 10 to the 6th W/sq cm, which gave temperature profiles, wave speed, etc. To pursue the propulsion application, a second computer model was developed to describe the acceleration of the gas emerging from the LSC wave into a variable-pressure, converging streamtube, still including all the above-mentioned physical processes. The results show very high temperatures in LSC waves which absorb all the laser energy, and high radiative losses.

  19. Detonation waves in relativistic hydrodynamics

    SciTech Connect

    Cissoko, M. )

    1992-02-15

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

  20. Evaluation of the oblique detonation wave ramjet

    NASA Technical Reports Server (NTRS)

    Morrison, R. B.

    1978-01-01

    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.

  1. Detonation wave augmentation of gas turbines

    NASA Technical Reports Server (NTRS)

    Wortman, A.

    1984-01-01

    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.

  2. Detonation wave compression in gas turbines

    NASA Technical Reports Server (NTRS)

    Wortman, A.

    1986-01-01

    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.

  3. High order hybrid numerical simulations of two dimensional detonation waves

    NASA Technical Reports Server (NTRS)

    Cai, Wei

    1993-01-01

    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.

  4. Detonation wave curvature of PBXN-111

    NASA Astrophysics Data System (ADS)

    Forbes, J. W.; Lemar, E. R.; Baker, R. N.

    1994-07-01

    Spherical curvatures of detonation waves were measured by streak photography over the center 50 percent of PBXN-111 charges. These curvatures range from 54 to 143 mm for charge diameters of 41 to 68 mm and are not spherical near the edges of the charges. The wave fronts appear linear over about the last 3 mm at the charges edges. The angle between the detonation wave front and the edge of the charge was about 62 degrees over this last 3 mm for all the charges. Detonation velocity and wave front curvature data of PBXN-111 were used to calculate CJ zone lengths of 2-4 mm using the Wood-Kirkwood theory.

  5. Effect of Resolution on Propagating Detonation Wave

    SciTech Connect

    Menikoff, Ralph

    2014-07-10

    Simulations of the cylinder test are used to illustrate the effect of mesh resolution on a propagating detonation wave. For this study we use the xRage code with the SURF burn model for PBX 9501. The adaptive mesh capability of xRage is used to vary the resolution of the reaction zone. We focus on two key properties: the detonation speed and the cylinder wall velocity. The latter is related to the release isentrope behind the detonation wave. As the reaction zone is refined (2 to 15 cells for cell size of 62 to 8μm), both the detonation speed and final wall velocity change by a small amount; less than 1 per cent. The detonation speed decreases with coarser resolution. Even when the reaction zone is grossly under-resolved (cell size twice the reaction-zone width of the burn model) the wall velocity is within a per cent and the detonation speed is low by only 2 per cent.

  6. Detonation wave profiles in HMX based explosives

    SciTech Connect

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

    1997-11-01

    Detonation wave profiles have been measured in several HMX based plastic bonded explosives including PBX9404, PBX9501, and EDC-37, as well as two HMX powders (coarse and fine) pressed to 65% of crystal density. The powders had 120 and 10 {micro}m average grain sizes, respectively. Planar detonations were produced by impacting the explosive with projectiles launched in a 72-mm bore gas gun. Impactors, impact velocity, and explosive thickness were chosen so that the run distance to detonation was always less than half the explosive thickness. For the high density plastic bonded explosives, particle velocity wave profiles were measured at an explosive/window interface using two VISAR interferometers. PMMA windows with vapor deposited aluminum mirrors were used for all experiments. Wave profiles for the powdered explosives were measured using magnetic particle velocity gauges. Estimates of the reaction zone parameters were obtained from the profiles using Hugoniots of the explosive and window.

  7. On the Existence of Pathological Detonation Waves

    SciTech Connect

    Tarver, C M

    2003-07-11

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

  8. Propagation of Sinusoidally-Corrugated Shock Fronts of Laser-Supported Detonations

    NASA Astrophysics Data System (ADS)

    Honda, T.; Kawaguchi, A.; Hanta, Y.; Susa, A.; Namba, S.; Johzaki, T.; Endo, T.; Shiraga, H.; Shigemori, K.; Koga, M.; Nagatomo, H.

    The behavior of sinusoidally-rippled shock fronts is a fundamental research topic in the dynamics of shock waves [1]. The Whitham's ray-shock theory, which is sometimes called the geometrical-shock-dynamics (GSD) theory, is known as a simple method for analyzing the behavior of a non-planar shock front. In this theory, narrow ray tubes corresponding to the light rays in the geometrical optics are placed perpendicularly to the every portions of a non-planar shock front, and the evolution of the shock front is calculated by tracking the shock front in each ray tube sequentially. When the behavior of an inert sinusoidally-rippled shock front is analyzed by the GSD theory and the Chester-Chisnell-Whitham's (CCW's) A-M relationship [2], where A is the cross-sectional area of a ray tube and M is the propagation Mach number of the shock wave in the ray tube, the amplitude of the shock-front ripple oscillates as the shock wave propagates [3]. Actually, the behavior of an inert sinusoidally-rippled shock front is influenced by the fluid motion in the shock-compressed region, and the amplitude of the shock-front ripple shows damped oscillation as the shock wave propagates [1,3,4,5].

  9. Analytical study of laser supported combustion waves in hydrogen

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    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.

  10. Detonation wave velocity and curvature of brass encased PBXN-111

    NASA Astrophysics Data System (ADS)

    Forbes, J. W.; Lemar, E. R.

    1996-05-01

    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.

  11. Mach reflection of a ZND detonation wave

    NASA Astrophysics Data System (ADS)

    Li, J.; Ning, J.; Lee, J. H. S.

    2015-05-01

    The Mach reflection of a ZND detonation wave on a wedge is investigated numerically. A two-step chain-branching reaction model is used giving a thermally neutral induction zone followed by a chemical reaction zone for the detonation wave. The presence of a finite reaction zone thickness renders the Mach reflection process non-self-similar. The variation of the height of the Mach stem with distance of propagation does not correspond to a straight curve from the wedge apex as governed by self-similar three-shock theory. However, the present results indicate that in the near field around the wedge apex, and in the far field where the reaction zone thickness is small compared to the distance of travel of the Mach stem, the behavior appears to be self-similar. This corresponds to the so-called frozen and equilibrium limit pointed out by Hornung and Sanderman for strong discontinuity shock waves and by Shepherd et al. for cellular detonations. The critical wedge angle for the transition from regular to Mach reflection is found to correspond to the value determined by self-similar three-shock theory, but not by reactive three-shock theory for a discontinuous detonation front.

  12. Detonation wave curvature of cast Comp B and PBXN-111

    NASA Astrophysics Data System (ADS)

    Lemar, E. R.; Forbes, J. W.

    1994-07-01

    Detonation wave profiles for cast Comp B and PBXN-111 have been fitted accurately over the entire wave fronts using a series expansion of the natural logarithm of a Bessel function. The fit equation has been used to obtain the angle of the detonation front as a function of position and the radii of curvature used in Wood-Kirkwood zone length calculations. The results obtained from the fit equation agree with results obtained previously for PBXN-111. Since the fit equation gives a functional form for the detonation wave across the whole charge diameter, it can be used to test the results obtained from detonation theories and code calculations.

  13. Detonation wave velocity and curvature of brass encased PBXN-111

    SciTech Connect

    Forbes, J.W.; Lemar, E.R.

    1996-05-01

    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.}

  14. Three dimensional hemispherical test development to evaluate detonation wave breakout

    NASA Astrophysics Data System (ADS)

    Francois, E. G.; Morris, J. S.; Lieber, M.

    2014-05-01

    The Onionskin test has been the standard test to evaluate detonation wave breakout over a hemispherical surface for decades. It has been an effective test used in a variety of applications to qualify main charge materials, evaluate different boosters, and compare different detonators. It is not without its shortfalls however. It only images a small portion of the explosive and requires very precise alignment and camera requirements to make sense of the results. Asymmetry in explosive behavior cannot be pinpointed or evaluated effectively. We have developed a new diagnostic using fiber optics covering the surface of the explosive to yield a 3D representation of the detonation wave behavior. Precise timing mapping of the detonation over the hemispherical surface is generated which can be converted to detonation wave breakout behavior using Huygens' wave reconstruction. This report will include the results of a recent suite of tests on PBX 9501, and discussion of how the test was developed for this explosive and contrasting previous work on PBX 9502. The results of these tests will describe the effects on detonation wave breakout symmetry when Sylgard 184 is placed between the detonator and booster. The effects on symmetry and timing when the Sylgard gap thickness is increased and the detonator is canted will be shown.

  15. Propagation of Axially Symmetric Detonation Waves

    SciTech Connect

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

    2002-06-26

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

  16. Links between detonation wave propagation and reactive flow models.

    SciTech Connect

    Swift, D. C.; White, S. J.

    2002-01-01

    An accurate reactive flow model is necessary to be able to predict the initiation properties of explosives by complicated shock structures, but a very fine the spatial resolution is needed in reactive flow to reproduce the detailed dynamics of a detonation wave. However, it is not often necessary to use a reactive flow model to simulate the motion of a fully-developed detonation wave. In many situations the same results can be obtained with a coarse computational mesh using programmed burn techniques. In the WBL model [Lambourn89,Swift93], an eikonal detonation wave propagates through a body of explosive at a speed which depends on the curvature of the wave. The model describes the motion of the leading shock of the detonation wave. Here we use the level set method for integrating the WBL equations in time [Collyer98,Bdzil93,Osher88,Aslam98]. This method is attractive because complicated detonation wave shapes can be represented simply. It was found possible to initialize the level set field by a set of source points derived from a reactive flow simulation, by taking 'trigger states' from the reactive flow. The level set scheme was generalized further to take account of motion of the material behind the detonation wave, allowing it to be used for simulations coupled with reactive flow, where detonation may propagate through preshocked and moving material. The modified level set scheme was implemented in 1D and 2D Lagrangian hydrocodes. Trial calculations were performed of initiation and detonation in the TATB-based explosive LX-17, using the Lee - Tarver model. A CJ detonation was simulated in order to verify that the modified level set algorithm operated correctly. The detonation speed was in very good agreement with the expected value. Single-shock initiation was simulated. The position - time history of the leading shock from the coupled model was in excellent agreement with full reactive flow; the pressure profiles were similar but not identical, because of the

  17. Weakly nonlinear dynamics of near-CJ detonation waves

    SciTech Connect

    Bdzil, J.B.; Klein, R.

    1993-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  19. Impact waves and detonation. Part I

    NASA Technical Reports Server (NTRS)

    Becker, R

    1929-01-01

    Among the numerous thermodynamic and kinetic problems that have arisen in the application of the gaseous explosive reaction as a source of power in the internal combustion engine, the problem of the mode or way by which the transformation proceeds and the rate at which the heat energy is delivered to the working fluid became very early in the engine's development a problem of prime importance. The work of Becker here given is a notable extension of earlier investigations, because it covers the entire range of the explosive reaction in gases - normal detonation and burning.

  20. Continuous detonation wave engine studies for space application

    NASA Astrophysics Data System (ADS)

    Davidenko, D. M.; Jouot, F.; Kudryavtsev, A. N.; Dupré, G.; Gökalp, I.; Daniau, E.; Falempin, F.

    2009-09-01

    Continuous Detonation Wave Rocket Engine (CDWRE) for space application is considered in the framework of French R&D and scientific research. A CDWRE demonstrator and a dedicated test bench are designed by MBDA France. At ICARE-CNRS, theoretical and experimental studies on the CDWRE internal processes are under progress. Twodimensional (2D) Euler simulations of a CDWRE combustion chamber have been performed to investigate the effect of geometrical and injection parameters on the internal process and combustion chamber performance. An experimental study is prepared to investigate liquid oxygen breakup and vaporization in a helium flow as well as detonation initiation and propagation in a spray of liquid oxygen/gaseous hydrogen.

  1. A Kinetic Approach to Propagation and Stability of Detonation Waves

    NASA Astrophysics Data System (ADS)

    Monaco, R.; Bianchi, M. Pandolfi; Soares, A. J.

    2008-12-01

    The problem of the steady propagation and linear stability of a detonation wave is formulated in the kinetic frame for a quaternary gas mixture in which a reversible bimolecular reaction takes place. The reactive Euler equations and related Rankine-Hugoniot conditions are deduced from the mesoscopic description of the process. The steady propagation problem is solved for a Zeldovich, von Neuman and Doering (ZND) wave, providing the detonation profiles and the wave thickness for different overdrive degrees. The one-dimensional stability of such detonation wave is then studied in terms of an initial value problem coupled with an acoustic radiation condition at the equilibrium final state. The stability equations and their initial data are deduced from the linearized reactive Euler equations and related Rankine-Hugoniot conditions through a normal mode analysis referred to the complex disturbances of the steady state variables. Some numerical simulations for an elementary reaction of the hydrogen-oxygen chain are proposed in order to describe the time and space evolution of the instabilities induced by the shock front perturbation.

  2. Propagation of Curved Detonation Waves Stabilized in Annular Channels with a Rectangular Cross-section

    NASA Astrophysics Data System (ADS)

    Nakayama, Hisahiro; Takahiro Moriya; Kasahara, Jiro; Matsuo, Akiko; Sasamoto, Yuya; Funaki, Ikkoh

    Visualization experiments employing rectangular cross-section curved channels were performed in order to examine the fundamental characteristics of a curved detonation wave propagating stably through an annular channel. A stoichiometric ethylene-oxygen mixture gas and five types of curved channels with different inner radii of curvature were used. The detonation waves propagating in the curved channels were curved due to the expansion waves from the inner walls of the curved channels. The ratio of the inner radius of curved channel (ri) to the normal detonation cell width (λ) was an important factor determining the stability of the curved detonation waves. The detonation propagation mode in the curved channels transitioned from unstable to stable in the range 14 ≤ ri/λ ≤ 26. The normal detonation velocity (Dn) of the curved detonation wave propagating stably in a curved channel was approximately formulated. The approximated Dn given by the formula agreed well with the experimental results. The front shock shape of the curved detonation wave could be reconstructed accurately using the formula. The value of Dn nondimensionalized by the Chapman-Jouguet detonation velocity became a function of the local curvature of the curved detonation wave (κ) nondimensionalized by λ regardless of the shape of curved channel. The front shock shapes of the detonation waves in the stable mode became similar to each other under constant ri/λ conditions.

  3. Numerical studies of shock focusing induced by reflection of detonation waves within a hemispherical implosion chamber

    NASA Astrophysics Data System (ADS)

    Hatanaka, K.; Saito, T.; Takayama, K.

    2012-11-01

    The initiation and the propagation of detonation waves in a hemispherical chamber and the imploding shock waves that are the reflected detonation waves at the chamber wall are numerically investigated. The effects of the boundary layer and the non-uniformity of the flow field induced by the detonation wave on the imploding shock stability are examined. It is found that the effect of the boundary layer separation on the chamber wall has the strongest effect on the implosion focus.

  4. Multi-frame visualization for detonation wave diffraction

    NASA Astrophysics Data System (ADS)

    Nagura, Y.; Kasahara, J.; Matsuo, A.

    2016-09-01

    When a detonation wave emerges from a tube into unconfined space filled with a gas mixture, detonation wave diffraction occurs due to abrupt changes in the cross-sectional area. In the present study, we focused on the local explosion in reinitiation and propagation of a transverse detonation wave by performing comprehensive and direct observation with high time resolution visualization in a two-dimensional rectangular channel. Using the visualization methods of shadowgraph and multi-frame, short-time, open-shutter photography, we determined where the wall reflection point is generated, and also determined where the bright point is originated by the local explosion, and investigated the effects of the deviation angle and initial pressure of the gas mixture. We found that the reinitiation of detonation had two modes that were determined by the deviation angle of the channel. If the deviation angle was less than or equal to 30°, the local explosion of reinitiation might occur in the vicinity of the channel wall, and if the deviation angle was greater than or equal to 60°, the local explosion might originate on the upper side of the tube exit. With a deviation angle greater than 60°, the position of the wall reflection point depended on the cell width, so the radial distance of the wall reflection point from the apex of the tube exit was about 12 times the cell width. Similarly, the bright point (local explosion point) was located a distance of about 11 times the cell width from the apex of the tube exit, with a circumferential angle of 48°.

  5. Multi-frame visualization for detonation wave diffraction

    NASA Astrophysics Data System (ADS)

    Nagura, Y.; Kasahara, J.; Matsuo, A.

    2016-05-01

    When a detonation wave emerges from a tube into unconfined space filled with a gas mixture, detonation wave diffraction occurs due to abrupt changes in the cross-sectional area. In the present study, we focused on the local explosion in reinitiation and propagation of a transverse detonation wave by performing comprehensive and direct observation with high time resolution visualization in a two-dimensional rectangular channel. Using the visualization methods of shadowgraph and multi-frame, short-time, open-shutter photography, we determined where the wall reflection point is generated, and also determined where the bright point is originated by the local explosion, and investigated the effects of the deviation angle and initial pressure of the gas mixture. We found that the reinitiation of detonation had two modes that were determined by the deviation angle of the channel. If the deviation angle was less than or equal to 30°, the local explosion of reinitiation might occur in the vicinity of the channel wall, and if the deviation angle was greater than or equal to 60°, the local explosion might originate on the upper side of the tube exit. With a deviation angle greater than 60°, the position of the wall reflection point depended on the cell width, so the radial distance of the wall reflection point from the apex of the tube exit was about 12 times the cell width. Similarly, the bright point (local explosion point) was located a distance of about 11 times the cell width from the apex of the tube exit, with a circumferential angle of 48°.

  6. Linear and nonlinear effects in detonation wave structure formation

    NASA Astrophysics Data System (ADS)

    Borisov, S. P.; Kudryavtsev, A. N.

    2016-06-01

    The role of linear and nonlinear effects in the process of formation of detonation wave structure is investigated using linear stability analysis and direct numerical simulation. A simple model with a one-step irreversible chemical reaction is considered. For linear stability computations, both the local iterative shooting procedure and the global Chebyshev pseudospectral method are employed. Numerical simulations of 1D pulsating instability are performed using a shock fitting approach based on a 5th order upwind-biased compact-difference discretization and a shock acceleration equation deduced from the Rankine-Hugoniot conditions. A shock capturing WENO scheme of the 5th order is used to simulate propagation of detonation wave in a plane channel. It is shown that the linear analysis predicts correctly the mode dominating on early stages of flow evolution and the size of detonation cells which emerge during these stages. Later, however, when a developed self-reproducing cellular structure forms, the cell size is approximately doubled due to nonlinear effects.

  7. On detonation wave front structure of consensed high explosives

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Menshikh, A. V.; Yagodin, N. B.

    1998-07-01

    The present report describes detonation front particle velocity profile measurements for three high explosives (HE). Two were plasticized compositions based on PETN, HMX, and the third a TNT/RDX 50/50 mixture. Measurements were carried out using laser interferometry techniques with few nanosecond time resolution. Particle velocity profiles were recorded at HE-window (lithium fluoride [LiF]) interfaces. The detonation waves were diverging since they developed from a single initiation point. Recorded maximum particle velocities at the LiF window interfaces for PETN, HMX, and TNT/RDX mixture were 2.7 mm/μs, 3.15 mm/μs and 2.6 mm/μs, respectively. Duration of chemical reaction zone for HEs based on PETN and HMX were determined. The results of linear extrapolation of recorded particle velocity to zero time are presented, leading to estimates of von Neumann spike parameters for the PETN and HMX compositions.

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

    SciTech Connect

    Li, J.; Lai, W.H.; Chung, K.; Lu, F.K.

    2008-08-15

    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)

  9. Detonation wave velocity and curvature of IRX-4 and PBXN-110

    NASA Astrophysics Data System (ADS)

    Lemar, E. R.; Forbes, J. W.; Sutherland, G. T.

    1996-05-01

    Detonation velocities and wave front curvatures were measured for bare cylindrical charges of IRX-4 and PBXN-110 charges. Steady detonation waves propagated in IRX-4 charges with diameters as small as 33 mm. The failure diameter of IRX-4 is between 25 and 33 mm. A fit of detonation velocity data gives 5.83 mm/μs for IRX-4's infinite diameter velocity. Detonation wave curvature experiments have been done on 48 mm diameter cylindrical IRX-4 charges with lengths from 9 to 28 cm. The data have been fitted accurately over the entire charge diameters using the natural logarithm of a Bessel function.

  10. Shock wave and detonation wave response of selected HMX based research explosives with HTPB binder systems

    NASA Astrophysics Data System (ADS)

    Sutherland, G. T.; Lemar, E. R.; Forbes, J. W.; Anderson, E.; Miller, P.; Ashwell, K. D.; Baker, R. N.; Liddiard, T. P.

    1994-07-01

    The sensitivity, detonation properties, and performance of selected HMX based explosives are compared. All explosives were manufactured using a hydroxyl-terminated polybutadiene (HTPB) binder system. IRX class explosives were manufactured to obtain explosives in which ingredients were systematically varied. The particle size range of the HMX particles was controlled by sieving. Sensitivity and performance experiments were conducted using the explosives IRX-1, and IRX-3A. These experiments measured: detonation pressure, detonation velocity, modified gap test shock sensitivity, and detonation wave curvature. Modified gap tests were also performed for SW-21 and PBXN-110. In addition, light gas gun experiments were performed in which reactive stress-time profiles were obtained for IRX-1 and PBXN-110.

  11. The ignition of carbon detonations via converging shock waves in white dwarfs

    SciTech Connect

    Shen, Ken J.; Bildsten, Lars E-mail: bildsten@kitp.ucsb.edu

    2014-04-10

    The progenitor channel responsible for the majority of Type Ia supernovae is still uncertain. One emergent scenario involves the detonation of a He-rich layer surrounding a C/O white dwarf, which sends a shock wave into the core. The quasi-spherical shock wave converges and strengthens at an off-center location, forming a second, C-burning, detonation that disrupts the whole star. In this paper, we examine this second detonation of the double detonation scenario using a combination of analytic and numeric techniques. We perform a spatially resolved study of the imploding shock wave and outgoing detonation and calculate the critical imploding shock strengths needed to achieve a core C detonation. We find that He detonations in recent two-dimensional simulations yield converging shock waves that are strong enough to ignite C detonations in high-mass C/O cores, with the caveat that a truly robust answer requires multi-dimensional detonation initiation calculations. We also find that convergence-driven detonations in low-mass C/O cores and in O/Ne cores are harder to achieve and are perhaps unrealized in standard binary evolution.

  12. Micro-blast waves using detonation transmission tubing

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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 < Δ {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.

  13. Effect of the initial pressure of multicomponent bubble media on the characteristics of detonation waves

    NASA Astrophysics Data System (ADS)

    Sychev, A. I.

    2016-05-01

    The effect of the initial pressure of multicomponent bubble media on the conditions of initiation, the structure, the velocity, and the pressure of detonation waves is experimentally studied. The variation of the initial pressure of a bubble medium is found to be an effective method to control the parameters of bubble detonation waves.

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

    NASA Astrophysics Data System (ADS)

    Gordon, J. Motos

    Optical forensics of explosion events can play a vital role in investigating the chain of events leading up to the explosion by possibly identifying key spectral characteristics and even molecules in the post-detonation fireball that may serve as the fingerprint for a particular explosive type used. This research characterizes the blast wave and temperature evolution of an explosion fireball in order to improve the classification of aluminized conventional munitions based on a single explosive type such as RDX. High speed 4 kHz visible imagery is collected for 13 field detonations of aluminized novel munitions to study fireball and shock wave dynamics. The 238 mus temporal resolution visible imagery and the 12 ms temporal resolution FTS spectra are the data sets upon which shock wave dynamics and the time dependence of the fireball temperature are studied, respectively. The Sedov-Taylor point blast theory is fitted to data where a constant release (s = 1) of energy upon detonation suggests shock energies of 0.5--8.9 MJ corresponding to efficiencies of 2--15 percent of the RDX heats of detonation with blast dimensionalities indicative of the spherical geometry observed in visible imagery. A drag model fit to data shows initial shock wave speeds of Mach 4.7--8.2 and maximum fireball radii ranging from 4.3--5.8 m with most of the radii reached by 50 ms upon detonation. Initial shock speeds are four times lower than theoretical maximum detonation speed of RDX and likely contributes to the low efficiencies. An inverse correlation exists between blast wave energy and overall aluminum or liner content in the test articles. A two-color best fit Planckian is used to extract temperature profiles from collected Fourier-transform spectrometer spectra. The temperatures decay from initial values of 1290--1850 K to less than 1000 K within 1 s after detonation. A physics-based low-dimensionality empirical model is developed to represent the temperature evolution of post-detonation

  15. Hydrodynamic instabilities and transverse waves in propagation mechanism of gaseous detonations

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  16. Precursor detonation wave development in ANFO due to aluminum confinement

    SciTech Connect

    Jackson, Scott I; Klyanda, Charles B; Short, Mark

    2010-01-01

    Detonations in explosive mixtures of ammonium-nitrate-fuel-oil (ANFO) confined by aluminum allow for transport of detonation energy ahead of the detonation front due to the aluminum sound speed exceeding the detonation velocity. The net effect of this energy transport on the detonation is unclear. It could enhance the detonation by precompressing the explosive near the wall. Alternatively, it could decrease the explosive performance by crushing porosity required for initiation by shock compression or destroying confinement ahead of the detonation. At present, these phenomena are not well understood. But with slowly detonating, non-ideal high explosive (NIHE) systems becoming increasing prevalent, proper understanding and prediction of the performance of these metal-confined NIHE systems is desirable. Experiments are discussed that measured the effect of this ANFO detonation energy transported upstream of the front by a 76-mm-inner-diameter aluminum confining tube. Detonation velocity, detonation-front shape, and aluminum response are recorded as a function of confiner wall thickness and length. Detonation shape profiles display little curvature near the confining surface, which is attributed to energy transported upstream modifying the flow. Average detonation velocities were seen to increase with increasing confiner thickness, while wavefront curvature decreased due to the stiffer, subsonic confinement. Significant radial sidewall tube motion was observed immediately ahead of the detonation. Axial motion was also detected, which interfered with the front shape measurements in some cases. It was concluded that the confiner was able to transport energy ahead of the detonation and that this transport has a definite effect on the detonation by modifying its characteristic shape.

  17. On the propagation mechanism of a detonation wave in a round tube with orifice plates

    NASA Astrophysics Data System (ADS)

    Ciccarelli, G.; Cross, M.

    2016-06-01

    This study deals with the investigation of the detonation propagation mechanism in a circular tube with orifice plates. Experiments were performed with hydrogen air in a 10-cm-inner-diameter tube with the second half of the tube filled with equally spaced orifice plates. A self-sustained Chapman-Jouguet (CJ) detonation wave was initiated in the smooth first half of the tube and transmitted into the orifice-plate-laden second half of the tube. The details of the propagation were obtained using the soot-foil technique. Two types of foils were used between obstacles, a wall-foil placed on the tube wall, and a flat-foil (sooted on both sides) placed horizontally across the diameter of the tube. When placed after the first orifice plate, the flat foil shows symmetric detonation wave diffraction and failure, while the wall foil shows re-initiation via multiple local hot spots created when the decoupled shock wave interacts with the tube wall. At the end of the tube, where the detonation propagated at an average velocity much lower than the theoretical CJ value, the detonation propagation is much more asymmetric with only a few hot spots on the tube wall leading to local detonation initiation. Consecutive foils also show that the detonation structure changes after each obstacle interaction. For a mixture near the detonation propagation limit, detonation re-initiation occurs at a single wall hot spot producing a patch of small detonation cells. The local overdriven detonation wave is short lived, but is sufficient to keep the global explosion front propagating. Results associated with the effect of orifice plate blockage and spacing on the detonation propagation mechanism are also presented.

  18. On the propagation mechanism of a detonation wave in a round tube with orifice plates

    NASA Astrophysics Data System (ADS)

    Ciccarelli, G.; Cross, M.

    2016-09-01

    This study deals with the investigation of the detonation propagation mechanism in a circular tube with orifice plates. Experiments were performed with hydrogen air in a 10-cm-inner-diameter tube with the second half of the tube filled with equally spaced orifice plates. A self-sustained Chapman-Jouguet (CJ) detonation wave was initiated in the smooth first half of the tube and transmitted into the orifice-plate-laden second half of the tube. The details of the propagation were obtained using the soot-foil technique. Two types of foils were used between obstacles, a wall-foil placed on the tube wall, and a flat-foil (sooted on both sides) placed horizontally across the diameter of the tube. When placed after the first orifice plate, the flat foil shows symmetric detonation wave diffraction and failure, while the wall foil shows re-initiation via multiple local hot spots created when the decoupled shock wave interacts with the tube wall. At the end of the tube, where the detonation propagated at an average velocity much lower than the theoretical CJ value, the detonation propagation is much more asymmetric with only a few hot spots on the tube wall leading to local detonation initiation. Consecutive foils also show that the detonation structure changes after each obstacle interaction. For a mixture near the detonation propagation limit, detonation re-initiation occurs at a single wall hot spot producing a patch of small detonation cells. The local overdriven detonation wave is short lived, but is sufficient to keep the global explosion front propagating. Results associated with the effect of orifice plate blockage and spacing on the detonation propagation mechanism are also presented.

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

    SciTech Connect

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

    2001-08-01

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

  20. Damage in Low Alloy Steel Produced by Sweeping, Interacting Detonation Waves

    NASA Astrophysics Data System (ADS)

    Hull, Lawrence; Gray, George; Faulkner, James; Briggs, Matthew

    2013-06-01

    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 where the waves collide that are impressed in an adjacent metal, causing similar stress gradients within the metal that often cause 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 consists 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. Calculations provide further insight into the loading conditions created by the sweeping, interacting detonation waves. Spall is indicated in most regions, but not some, and the alpha-epsilon stress-induced phase transformation appears in most regions, but not all. Correlations of the observed physical effects with incident wave obliquity and transverse position relative to the wave interactions are discussed.

  1. Numerical study of detonation wave propagation in a confined supersonic flow

    NASA Astrophysics Data System (ADS)

    Yi, T. H.; Lu, F. K.; Wilson, D. R.; Emanuel, G.

    2016-07-01

    The dynamics of detonation waves propagating in a confined supersonic flow is numerically investigated to understand the effects of incoming flow velocity in a combustion chamber on detonation properties and structure. The computational code is based on the Euler equations with detailed chemistry. The detonation is directly initiated with high pressure and temperature at a given region inside a straight tube and then propagates both upstream and downstream. The study shows that as the incoming flow velocity increases, the properties of the detonation wave moving upstream and downstream are significantly changed. This leads to an increase or decrease in the velocity and strength of the detonation wave, and a change in smoked foil cellular pattern. It was found that the strength of the upstream-moving detonation becomes higher and the propagation velocity decreases as the incoming velocity increases. These factors result in a change of the smoked foil pattern such as the cell length, width, and track angle. Moreover, the time in stabilizing the detonations moving in opposite directions is significantly changed with a supersonic incoming flow. An initiation delay occurs on the downstream-moving detonation since it is weakened in a supersonic flow.

  2. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-07-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  3. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-09-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

    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

  5. Propagation of detonation wave in hydrogen-air mixture in channels with sound-absorbing surfaces

    NASA Astrophysics Data System (ADS)

    Bivol, G. Yu.; Golovastov, S. V.; Golub, V. V.

    2015-12-01

    The possibility of using sound-absorbing surfaces for attenuating the intensity of detonation waves propagating in hydrogen-air mixtures has been experimentally studied in a cylindrical detonation tube open at one end, with an explosive initiated by spark discharge at the closed end. Sound-absorbing elements were made of an acoustic-grade foamed rubber with density of 0.035 g/cm3 containing open pores with an average diameter of 0.5 mm. The degree of attenuation of the detonation wave front velocity was determined as dependent on the volume fraction of hydrogen in the gas mixture.

  6. Unsteady Propagation Process of Oblique Detonation Waves Initiated by Hypersonic Spherical Projectiles

    NASA Astrophysics Data System (ADS)

    Maeda, Shinichi; Kasahara, Jiro; Matsuo, Akiko

    A spherical projectile was launched with 110% - 180% of a Chapman-Jouget (C-J) velocity into a detonable mixture, and we investigated the oblique detonation wave (ODW) that stabilized around it. High time-resolution visualizations were conducted using a high-speed camera with 1-μs frame speed to directly confirm the ODW stabilization and to investigate an unsteady phenomenon observed near the stabilizing criticality. In this case, the ODW was a three-dimensional conical wave, and the curvature effect on the conical detonation wave is not negligible near a projectile. We investigated the wave velocity distribution along the wave and revealed that it had a local minimum point at 0.8 - 0.9 times a C-J velocity during the decay process from an overdriven detonation near a projectile to a C-J ODW in the far field. We defined a characteristic wave curvature radius normalized by a cell size on this local minimum point. In this study, the minimum characteristic wave curvature radius of about 18 was needed to stabilize the conical detonation wave around a sphere. Near the stabilizing criticality, we also observed the unsteady ODW stabilization or detonation initiation on a shock-induced combustion. This unsteady regime was characterized by periodical onsets of local explosions that initiate or stabilize an ODW. We investigated the wave velocity distribution along this regime, and our findings revealed that the ODW transition or the detonation initiation following the shock-induced combustion occurred when the wave velocity decayed to 0.5 - 0.6 times a C-J velocity.

  7. Super-equilibrium increase of chemical reaction rate in the detonation front and other effects in the detonation wave initiated by a shock wave

    NASA Astrophysics Data System (ADS)

    Kulikov, S. V.

    2013-11-01

    In the present work the problem of detonation wave formation in a shock tube was considered in one-dimensional formulation. The Monte Carlo non-stationary method of statistical simulation (MCNMSS), also known as DSMC, was used for simulation. The method automatically takes into account all details of mass and heat transfer. At an initial moment, the low-pressure channel (LPC) of the shock tube was filled with gas A while the high-pressure chamber (HPC) was filled with gas C. The cross-sections of the HPC and LPC, as well as the temperatures of gases A and C were equal to each other. At the beginning of the simulation the ratio of pressures in the HPC and LPC was equal to 100. It was assumed that chemical reactions ( and ) took place. The ratio of molecular masses of gases and was taken as 20:20:1. Different reaction thresholds were considered. For the case of a low reaction threshold, the velocity of the resulting detonation wave was found to be higher than the Chapman-Jouguet velocity. A region with constant values of flow parameters inside product was observed. An increase of the reaction threshold led to disappearance of this region and gave rise to something similar to an expansion wave, with peaks of flow parameters at the leading part of the detonation wave. The values of these peaks were found to be constant in time. The velocity of the detonation wave became appreciably lower than the Chapman-Jouguet velocity. Further increase of the reaction threshold led to disappearance of detonation. The reactions and turned out to be very important for initiation of detonation.

  8. Microscopic simulations of supersonic and subsonic exothermic chemical wave fronts and transition to detonation.

    PubMed

    Lemarchand, A; Nowakowski, B; Dumazer, G; Antoine, C

    2011-01-21

    We perform microscopic simulations using the direct simulation Monte Carlo approach to an exothermic chemical wave front of Fisher-Kolmogorov, Petrovsky, Piskunov-type in a one-dimensional gaseous medium. The results confirm the existence of a transition from a weak detonation or deflagration to a Chapman-Jouguet detonation wave, that we already investigated at the macroscopic scale [G. Dumazer et al., Phys. Rev. E 78, 016309 (2008)]. In the domain of weak detonation or deflagration, the discrepancy between the propagation speeds deduced from the simulations and the macroscopic balance equations of hydrodynamics is explained by two microscopic effects, the discretization of the variables, known as cutoff effect, and the departure from local equilibrium. Remarkably, the propagation speed of a Chapman-Jouguet detonation wave is not sensitive to these perturbations of microscopic origin. PMID:21261344

  9. Microscopic simulations of supersonic and subsonic exothermic chemical wave fronts and transition to detonation.

    PubMed

    Lemarchand, A; Nowakowski, B; Dumazer, G; Antoine, C

    2011-01-21

    We perform microscopic simulations using the direct simulation Monte Carlo approach to an exothermic chemical wave front of Fisher-Kolmogorov, Petrovsky, Piskunov-type in a one-dimensional gaseous medium. The results confirm the existence of a transition from a weak detonation or deflagration to a Chapman-Jouguet detonation wave, that we already investigated at the macroscopic scale [G. Dumazer et al., Phys. Rev. E 78, 016309 (2008)]. In the domain of weak detonation or deflagration, the discrepancy between the propagation speeds deduced from the simulations and the macroscopic balance equations of hydrodynamics is explained by two microscopic effects, the discretization of the variables, known as cutoff effect, and the departure from local equilibrium. Remarkably, the propagation speed of a Chapman-Jouguet detonation wave is not sensitive to these perturbations of microscopic origin.

  10. Detonation wave velocity and curvature of IRX-4 and PBXN-110

    SciTech Connect

    Lemar, E.R.; Forbes, J.W.; Sutherland, G.T.

    1996-05-01

    Detonation velocities and wave front curvatures were measured for bare cylindrical charges of IRX-4 and PBXN-110 charges. Steady detonation waves propagated in IRX-4 charges with diameters as small as 33 mm. The failure diameter of IRX-4 is between 25 and 33 mm. A fit of detonation velocity data gives 5.83 mm/{mu}s for IRX-4{close_quote}s infinite diameter velocity. Detonation wave curvature experiments have been done on 48 mm diameter cylindrical IRX-4 charges with lengths from 9 to 28 cm. The data have been fitted accurately over the entire charge diameters using the natural logarithm of a Bessel function. {copyright} {ital 1996 American Institute of Physics.}

  11. Analysis of supercritical vapor explosions using thermal detonation wave theory

    SciTech Connect

    Shamoun, B.I.; Corradini, M.L.

    1995-09-01

    The interaction of certain materials such as Al{sub 2}O{sub 3} with water results in vapor explosions with very high (supercritical) pressures and propagation velocities. A quasi-steady state analysis of supercritical detonation in one-dimensional multiphase flow was applied to analyze experimental data of the KROTOS (26-30) set of experiments conducted at the Joint Research Center at Ispra, Italy. In this work we have applied a new method of solution which allows for partial fragmentation of the fuel in the shock adiabatic thermodynamic model. This method uses known experiment values of the shock pressure and propagation velocity to estimate the initial mixing conditions of the experiment. The fuel and coolant were both considered compressible in this analysis. In KROTOS 26, 28, 29, and 30 the measured values of the shock pressure by the experiment were found to be higher than 25, 50, 100, and 100 Mpa respectively. Using the above data for the wave velocity and our best estimate for the values of the pressure, the predicted minimum values of the fragmented mass of the fuel were found to be 0.026. 0.04, 0.057, and 0.068 kg respectively. The predicted values of the work output corresponding to the above fragmented masses of the fuel were found to be 40, 84, 126, and 150 kJ respectively, with predicted initial void fractions of 112%, 12.5%, 8%, and 6% respectively.

  12. Detonation wave structure studies in high explosives by means of proton radiography

    NASA Astrophysics Data System (ADS)

    Kolesnikov, Sergei; Dudin, Sergei; Mintsev, Victor; Utkin, Alexander; Demidov, Victor; Fertman, Alexander; Golubev, Alexander; Katz, Mark; Markov, Nikolai; Sharkov, Boris; Smirnov, Gennady; Turtikov, Vladimir

    2007-06-01

    Proton radiography is the unique experimental technique for obtaining direct information about important material characteristics of real solid objects under dynamic conditions. The aim of the present work is the application of this method to the investigation of evolution of density in shock and detonation waves in high explosives (HE). Obtained information will be very useful for the improvement of existing detonation models and equations of state of HE. For this purpose a proton radiography facility for dynamic experiments on the basis of TWAC-ITEP accelerator is being constructed. A special containment chamber for explosive experiments was built. Static experiments with imitators of detonating HE charges were performed; as a result the proton radiographic images of imitators with time resolution of up to 10 ns were obtained. Dynamic experiments on the registration of detonation wave structure in pressed TNT are underway.

  13. The stabilization of unstable detonation waves for the mixture of nitromethane/methanol

    NASA Astrophysics Data System (ADS)

    Utkin, A. V.; Koldunov, S. A.; Mochalova, V. M.; Torunov, S. I.; Lapin, S. M.

    2015-11-01

    Using a laser interferometer VISAR the measurements of the particle velocity profiles in detonation waves for nitromethane/methanol mixtures with additions of a sensitizer diethylenetriamine were conducted. It is shown that the detonation front in a mixture of nitromethane/methanol is unstable and sensitizer is an effective method for the flow stabilization. If the diluent concentration is less than 10%, the detonation front is stabilized by adding of 1% diethylenetriamine. At higher concentrations of methanol, the sensitizer does not reject instability, but the amplitude of oscillations decreases in several times. An increase of the limit concentration of methanol at the addition of diethylenetriamine to the mixture was found.

  14. Pressure estimation for a low-speed detonation wave in pressed TEN

    SciTech Connect

    Martynyuk, V.F.; Sulimov, A.A.; Sukoyan, M.K.; Obmenin, A.V.

    1988-05-01

    This paper examined the dynamic deformation in steel shells with stationary low-speed detonation propagating in pressed TEN. Shell expansion was recorded with a ZhLV-2 triggered photographic system with the shell seen against a bright screen. The pressure pattern behind the front was shown to be stationary by the constant mode of shell expansion. Pressure in the stationary low-speed detonation was estimated from the photographic data. An expression was derived for calculating the estimated pressure from an equation for radial expansion of the shell. A dynamic deformation pattern was found which was used to calculate the explosive burnup in stationary low-speed detonation waves.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    SciTech Connect

    Tong Huifeng; Yuan Hong; Tang Zhiping

    2013-01-28

    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.

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

    NASA Astrophysics Data System (ADS)

    Tong, Huifeng; Yuan, Hong; Tang, Zhiping

    2013-01-01

    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.

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

    SciTech Connect

    Tarver, C M; McGuire, E M

    2002-07-01

    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.

  19. The evolution of a detonation wave in a variable cross-sectional chamber

    NASA Astrophysics Data System (ADS)

    Qu, Qing; Khoo, Boo Cheong; Dou, Hua-Shu; Tsai, Her Mann

    2008-08-01

    A two-dimensional numerical simulation has been performed to study the interaction of a gaseous detonation wave with obliquely inclined surfaces in a variable cross-sectional chamber. The weighted essentially non-oscillatory (WENO) numerical scheme with a relatively low resolution grid is employed. A detailed elementary chemical reaction model with 9 species and 19 elementary reactions is used for a stoichiometric oxy-hydrogen mixture diluted with argon. In this work, we study the effect of area expansion and contraction on the main/gross features of the detonation cellular structures in the presence of detonation reflection, diffraction and localized explosion. The result shows that there exists a transition region as the detonation wave propagates through the converging/diverging chamber. Within the transition region, the initial regular detonation cells become distorted and irregular before they re-obtain their regularity. While the ultimate regular cell size and the length of the transition region are strongly affected by the converging/diverging angle, the width/length ratio of the cells is fairly independent of it. A localized explosion near the wall is found as the detonation wave propagates in the diverging chamber.

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

    NASA Astrophysics Data System (ADS)

    Murphy, Michael J.; Adrian, Ronald J.

    2007-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Lemar, E. R.; Forbes, J. W.; Cowperthwaite, M.

    1998-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    A shock wave driven by millimeter wave ionization can be applied into a pulsed detonation engine as a Microwave Rocket. A high pressure induced inside the thruster generates the thrust, thus the shock wave propagation driven by the plasma is important. In this study, to obtain a different propagating structure, the beam profile was transformed from a Gaussian into a Ring and a Flat-top profile by using a pair of phase correcting mirrors. As a result, the shape of the propagating plasma was changed into a no-center shape in case of the Ring beam, and it was changed to a wider shape in case of the Flat-top beam. The propagating velocity of the ionization front of the Flat-top beam was much lower than that of the Gaussian due to the lower peak power density, and a higher plateau pressure and higher thrust impulse were generated by the Flat-top beam.

  3. Detonation Waves Parameters for Fefo/nitrobenzene Solution

    NASA Astrophysics Data System (ADS)

    Mochalova, V. M.; Utkin, A. V.; Garanin, V. A.; Torunov, S. I.

    2009-12-01

    The dependence of detonation parameters for (bis-(2-fluoro-2, 2-dinitroethyl) formal)/nitrobenzene solution (FEFO/NB) on NB concentration was defined. Velocity profiles of the boundary between HE and water window were recorded by laser interferometer VISAR. It was found that particle velocity in a pure FEFO was strongly oscillating with the oscillation amplitude ˜50 m/s. It means that detonation front is unstable and heterogeneities size is about 10 μm. The average velocity profile corresponds to ZND model. The reaction time is equal to ˜400 ns, C-J pressure and particle velocity are 24 GPa and 2.0 km/s respectively. For FEFO/NB solution it was found that at low NB concentrations (10-20%) oscillations disappeared and detonation front was stable. When the NB concentration increased up to 30% high-frequency oscillations appeared again. The measurements of reaction zone structure up to critical concentration were conducted, it was about 45%. At average particle velocity profiles Von Neumann spike was distinctly registered. It was shown that in a pure FEFO and in solutions with NB concentration exceeding 30%) detonation front was unstable.

  4. Detonation waves parameters for FEFO/nitrobenzene solution

    NASA Astrophysics Data System (ADS)

    Mochalova, Valentina; Utkin, Alexander; Garanin, Victor; Torunov, Sergey

    2009-06-01

    The dependence of detonation parameters for (bis-(2-fluoro-2,2-dinitroethyl) formal)/nitrobenzene solution (FEFO/NB) from NB concentration was defined. Velocity profiles of the boundary between HE and water window were recorded by laser interferometer VISAR. It was found that particle velocity in a pure FEFO was strongly oscillating with the oscillation amplitude ˜50 m/s. It means that detonation front is unstable and irregularity size is about 10 mkm. The average velocity profile corresponds to ZND model. The reaction time is equal to ˜ 400ns, C-J pressure and particle velocity are 24 GPa and 2.0 km/s respectively. For FEFO/NB solution it was found that at low NB concentrations (10-20%) oscillations disappeared and detonation front was stable. When the NB concentration was increased up to 30 % high-frequency oscillations appeared again. The measurements of reaction zone structure up to critical concentration were conducted, it was about 45%. At average particle velocity profiles Von Neumann spike was distinctly registered. It was shown that in a pure FEFO and in solutions with NB concentration exceeding 30% detonation front was unstable.

  5. Equilibrium and stability properties of detonation waves in the hydrodynamic limit of a kinetic model

    NASA Astrophysics Data System (ADS)

    Marques, Wilson, Jr.; Jacinta Soares, Ana; Pandolfi Bianchi, Miriam; Kremer, Gilberto M.

    2015-06-01

    A shock wave structure problem, like the one which can be formulated for the planar detonation wave, is analyzed here for a binary mixture of ideal gases undergoing the symmetric reaction {{A}1}+{{A}1}\\rightleftharpoons {{A}2}+{{A}2}. The problem is studied at the hydrodynamic Euler limit of a kinetic model of the reactive Boltzmann equation. The chemical rate law is deduced in this frame with a second-order reaction rate, in a chemical regime such that the gas flow is not far away from the chemical equilibrium. The caloric and the thermal equations of state for the specific internal energy and temperature are employed to close the system of balance laws. With respect to other approaches known in the kinetic literature for detonation problems with a reversible reaction, this paper aims to improve some aspects of the wave solution. Within the mathematical analysis of the detonation model, the equation of the equilibrium Hugoniot curve of the final states is explicitly derived for the first time and used to define the correct location of the equilibrium Chapman-Jouguet point in the Hugoniot diagram. The parametric space is widened to investigate the response of the detonation solution to the activation energy of the chemical reaction. Finally, the mathematical formulation of the linear stability problem is given for the wave detonation structure via a normal-mode approach, when bidimensional disturbances perturb the steady solution. The stability equations with their boundary conditions and the radiation condition of the considered model are explicitly derived for small transversal deviations of the shock wave location. The paper shows how a second-order chemical kinetics description, derived at the microscopic level, and an analytic deduction of the equilibrium Hugoniot curve, lead to an accurate picture of the steady detonation with reversible reaction, as well as to a proper bidimensional linear stability analysis.

  6. Detailed simulation of the pulsating detonation wave in the shock-attached frame

    NASA Astrophysics Data System (ADS)

    Lopato, A. I.; Utkin, P. S.

    2016-05-01

    The paper is devoted to the numerical investigation of the stability of propagation of pulsating gas detonation waves. For various values of the mixture activation energy, detailed propagation patterns of the stable, weakly unstable, irregular, and strongly unstable detonation are obtained. The mathematical model is based on the Euler system of equations and the one-stage model of chemical reaction kinetics. The distinctive feature of the paper is the use of a specially developed computational algorithm of the second approximation order for simulating detonation wave in the shock-attached frame. In distinction from shock capturing schemes, the statement used in the paper is free of computational artifacts caused by the numerical smearing of the leading wave front. The key point of the computational algorithm is the solution of the equation for the evolution of the leading wave velocity using the second-order grid-characteristic method. The regimes of the pulsating detonation wave propagation thus obtained qualitatively match the computational data obtained in other studies and their numerical quality is superior when compared with known analytical solutions due to the use of a highly accurate computational algorithm.

  7. Periodic oscillation and fine structure of wedge-induced oblique detonation waves

    NASA Astrophysics Data System (ADS)

    Gui, Ming-Yue; Fan, Bao-Chun; Dong, Gang

    2011-12-01

    An oblique detonation wave for a Mach 7 inlet flow over a long enough wedge of 30° turning angle is simulated numerically using Euler equation and one-step rection model. The fifth-order WENO scheme is adopted to capture the shock wave. The numerical results show that with the compression of the wedge wall the detonation wave front structure is divided into three sections: the ZND model-like strcuture, single-sided triple point structure and dual-headed triple point strucuture. The first structure is the smooth straight, and the second has the characteristic of the triple points propagating dowanstream only with the same velocity, while the dual-headed triple point structure is very complicated. The detonation waves facing upstream and downstream propagate with different velocities, in which the periodic collisions of the triple points cause the oscillation of the detonation wave front. This oscillation process has temporal and spatial periodicity. In addition, the triple point trace are recorded to obtain different cell structures in three sections.

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

    SciTech Connect

    Clarke, J.F.; Karni, S.; Quirk, J.J.; Roe, P.L.; Simmonds, L.G.; Toro, E.F. )

    1993-06-01

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

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

    SciTech Connect

    Lemar, E.R.; Forbes, J.W.; Cowperthwaite, M.

    1998-07-01

    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.}

  10. Critical deflagration waves leading to detonation onset under different boundary conditions

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    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.

  12. Numerical investigation of shock wave reflections near the head ends of rotating detonation engines

    NASA Astrophysics Data System (ADS)

    Zhou, R.; Wang, J.-P.

    2013-09-01

    The influence of various chamber geometries on shock wave reflections near the head end of rotating detonation engines was investigated. A hydrogen/air one-step chemical reaction model was used. The results demonstrated that the variation in flow field along the radial direction was not obvious when the chamber width was small, but became progressively more obvious as the chamber width increased. The thrust increased linearly, and the detonation height and the fuel-based gross specific impulse were almost constant as the chamber width increased. Near the head end, shock waves reflected repeatedly between the inner and outer walls. Both regular and Mach reflections were found near the head end. The length of the Mach stem increased as the chamber length increased. When the chamber width, chamber length and injection parameters were the same, the larger inner radius resulted in more shock wave reflections between the inner and outer walls. The greater the ratio of the chamber width to the inner radius, the weaker the shock wave reflection near the head end. The detonation height on the outer wall and the thrust, both increased correspondingly, while the specific impulse was almost constant as the inner radius of the chamber increased. The numerical shock wave reflection phenomena coincided qualitatively with the experimental results.

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

    NASA Astrophysics Data System (ADS)

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

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

  14. Scale effect of spherical projectiles for stabilization of oblique detonation waves

    NASA Astrophysics Data System (ADS)

    Maeda, S.; Sumiya, S.; Kasahara, J.; Matsuo, A.

    2015-03-01

    Oblique detonation waves (ODWs) were stabilized by launching a spherical projectile with 1.2-1.4 times the Chapman-Jouguet (C-J) velocity into detonable mixtures at rest. We used smaller projectiles (3.18 mm diameter) than those (4.76 mm diameter) in our previous studies and investigated the effect of the projectile scale on the stabilization of ODWs. We carried out high time resolution schlieren visualization using a high-speed camera. The detonable mixtures used were stoichiometric oxygen mixtures with acetylene, ethylene or hydrogen. They were diluted with argon with a 50 % volumetric fraction, and a dilute mixture containing 75 % argon was also tested for the acetylene/oxygen mixture. Here, we discuss the detonation stability in terms of the curvature effect arising from the three-dimensional nature of a stabilized ODW around a projectile. The curvature effect attenuated the detonation wave to below its C-J velocity in the vicinity of the projectile before the wave velocity asymptotically reached the C-J velocity in the far field. Our previous study showed that the propagation limit of the curvature effect is responsible for the stabilizing criticality of detonation waves. By obtaining detailed distributions of the wave propagation velocity and radius of curvature at the stabilizing criticality, we showed that the radius of curvature at the local minimum point of the wave propagation velocity represents the critical radius of curvature required for curved self-sustained detonation. In this study, we focused on this critical mode of the stabilized ODW for a small projectile (3.18 mm diameter). Distributions of the wave velocity and radius of curvature were obtained in the critical mode of the stabilized ODW. We compare these distributions with those for a larger projectile (4.76 mm diameter) and discuss the stabilizing criticality. For the small projectile, the observed combustion regimes had qualitatively the same trend for the initial pressure of the mixture

  15. Neutrino and gravitational wave signal of a delayed-detonation model of type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Seitenzahl, Ivo R.; Herzog, Matthias; Ruiter, Ashley J.; Marquardt, Kai; Ohlmann, Sebastian T.; Röpke, Friedrich K.

    2015-12-01

    The progenitor system(s) and the explosion mechanism(s) of type Ia supernovae (SNe Ia) are still under debate. Nonelectromagnetic observables, in particular, gravitational waves and neutrino emission, of thermoclear supernovae are a complementary window to light curves and spectra for studying these enigmatic objects. A leading model for SNe Ia is the thermonuclear incineration of a near-Chandrasekhar mass carbon-oxygen white dwarf star in a "delayed detonation." We calculate a three-dimensional hydrodynamic explosion for the N100 delayed-detonation model extensively discussed in the literature, taking the dynamical effects of neutrino emission from all important contributing source terms into account. Although neutrinos carry away 2 ×1049 erg of energy, we confirm the common view that neutrino energy losses are dynamically not very important, resulting in only a modest reduction of final kinetic energy by 2%. We then calculate the gravitational wave signal from the time evolution of the quadrupole moment. Our model radiates 7 ×1039 erg in gravitational waves and the spectrum has a pronounced peak around 0.4 Hz. Depending on viewing angle and polarization, we find that the future space-based gravitational wave missions DECIGO and BBO would be able to detect our source to a distance of ˜1.3 Mpc . We predict a clear signature of the deflagration-to-detonation transition in the neutrino and the gravitational wave signals. If observed, such a feature would be a strong indicator of the realization of delayed detonations in near-Chandrasekhar mass white dwarfs.

  16. Influence of Sample Geometry on Sweeping-Detonation-Wave Spallation in Tantalum

    NASA Astrophysics Data System (ADS)

    Gray, George, III; Hull, Larry; Livescu, Veronica; Briggs, Matt; Meyer, Ross; Los Alamos National Laboratory Team

    2015-06-01

    Widespread research over the past five decades has provided a wealth of experimental data and insight concerning shock hardening and the spallation response of materials subjected to square-topped shock-wave loading profiles. Less quantitative data have been gathered on the effect of direct, in-contact, sweeping-wave high explosive (HE)-driven Taylor wave loading profile shock loading on the shock hardening, damage evolution, or spallation response of materials. Sweeping-wave loading is a significantly different loading history than that achieved by a square-topped impulse or 1-D HE-driven plane-wave shock in terms of the evolving spherical and shear stresses applied to the specimen. The goal of this research is to quantify the combined influence of shockwave obliquity evolution plus sample geometry on the spallation response of Tantalum(Ta) by subjecting a curved Ta plate to HE-driven sweeping detonation-wave loading and quantify both the wave propagation and the post-mortem damage evolution. This talk will summarize our current understanding of the similarity and differences between the shock hardening and damage evolution during sweeping detonation-wave spallation loading observed in flat and curved Ta plate samples.

  17. On self-similar blast waves headed by the Chapman-Jouguet detonation.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.; Kuhl, A. L.; Kamel, M. M.

    1972-01-01

    Consideration of the whole class of self-similar solutions for blast waves bounded by Chapman-Jouguet detonations that propagate into a uniform, quiescent, zero counterpressure atmosphere of a perfect gas with constant specific heats. Since such conditions can be approached quite closely by some actual chemical systems at NTP, this raises the interesting possibility of the existence of Chapman-Jouguet detonations of variable velocity. The principal virtue of the results presented is, however, more of theoretical significance. They represent the limiting case for all the self-similar blast waves headed by gasdynamic discontinuities associated with a deposition of finite amounts of energy, and they exhibit some unique features owing to the singular nature of the Chapman-Jouguet condition.

  18. Computational and theoretical analysis of weak and strong transverse-wave structures in gaseous detonations

    SciTech Connect

    Deiterding, Ralf

    2011-01-01

    Two-dimensional simulation results are presented that capture at great detail the temporal evolution of Mach reflection triple point sub-structures intrinsic to gaseous detonation waves. The observed patterns are classified by shock polar analysis for realistic, thermally perfect but nonreactive gases. A diagram of the transition boundaries between possible Mach reflection structures is constructed and found to be in good agreement with the computational results.

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

    NASA Technical Reports Server (NTRS)

    Fleming, Kevin J.

    1993-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Miller, Cearcy D

    1946-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  2. Velocity Fluctuations in the Interaction of Homogeneous, Isotropic Turbulence and a Detonation Wave

    NASA Astrophysics Data System (ADS)

    Hussein, S. M.; Blaiszik, E. M.; Baydar, E.; Lu, F. K.

    The canonical problem of a shock wave interacting with homogeneous, isotropic turbulence (STI) has been well studied for over 40 years [1] and remains a topic of interest [2, 3]. One of the motivations for studying this canonical STI problem is that it captures key physics of the complex viscous-inviscid interaction that occur in other more realistic situations such as shock/boundary-layer interactions. A relatively less well-studied problem is the interaction with a detonation wave (DTI), with initial studies dating to almost as far back [4, 5].

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

    SciTech Connect

    Gustavsen, Richard L; Bartram, Brian D; Sanchez, Nathaniel J

    2009-01-01

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

  4. Analytical and experimental investigations of the oblique detonation wave engine concept

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  5. Analytical and experimental investigations of the oblique detonation wave engine concept

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  6. A numerical investigation of the prompt oblique detonation wave sustained by a finite-length wedge

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Han, Xudong; Yao, Songbai; Wang, Jianping

    2016-03-01

    The prompt oblique detonation wave (PODW) sustained by a finite-length wedge is investigated by numerical simulation. The numerical results show that it is possible to stabilize a PODW on a finite-length wedge shorter than the induction length of the mixture behind the inert shock by numerically imposing a premature initiation of combustion in the initial flow field. The fully coupled and the partially coupled PODWs are observed in the numerical results. For the fully coupled PODW, the upstream facing transverse waves (UF TW) are swept downstream and consequently a fully coupled PODW can persist. For the partially coupled PODW, the UF TWs propagate upstream and the downstream facing transverse waves are weakened by the expansion wave emanating from the corner. As a result, a partially coupled PODW forms. Further, it is found that the stability of the partially coupled PODW is weak. The configuration of the partially coupled PODW can be altered by local explosions occurring downstream.

  7. The formation of an overdriven detonation wave in the flow of methane-oxygen mixtures in a channel of variable cross section

    NASA Astrophysics Data System (ADS)

    Bivol, G. Yu; Golovastov, S. V.; Golub, V. V.

    2015-11-01

    Formation of an overdriven detonation wave in methane-oxygen mixtures in a channel was investigated experimentally The gas mixture was ignited by a spark gap, located at the closed end of the combustion chamber. To create the overdriven detonation wave, a decay of the stationary detonation wave in the transition to a channel with a larger cross-section was carried out. Then, a complex of a shock wave and flame front moved into the channel with converging section. Formation of the overdriven detonation wave with parameters several times greater than those of the Chapman-Jouguet detonation was recorded at the outlet of the conical section. The velocities of the detonation front depend upon the composition of the mixture.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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 infinitesmal 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.

  9. H{sub 2}-air and CH{sub 4}-air detonations and combustions behind oblique shock waves

    SciTech Connect

    Viguier, C.; Guerraud, C.; Desbordes, D.

    1994-12-31

    Two stoichiometric reactive mixtures (H{sub 2}-air and CH{sub 4}-air) at initial conditions of temperature and pressure, T{sub 0} = 293 K and p{sub 0} < 1 bar, respectively, very different from the point of view of their detonability, are used in order to study the conditions of the onset of combustion and/or detonation when submitted to the action of an oblique shock wave (OSW) at Mach number M of about 6 and at various angles of inclination {theta}. Generation of an OSW in the reactive mixture at rest is obtained via lateral expansion of the detonation products of a normal CJ detonation wave propagating in a bounded gaseous detonable mixture separated from the mixture under test by a 6-{micro}m-thick mylar film. Different steady combustion regimes are observed depending on {theta} and on the reactive mixture. Based on simple polars analysis, the possibility of observing an oblique detonation wave (ODW) are checked for the two mixtures. In the case of H{sub 2}-air mixtures, ODWs are obtained with small degrees of overdrive (D/D{sub CJ}) ({approx_equal} 1) of the detonation (where D is the normal detonation velocity of the ODW) after a predetonation zone, where the OSW is followed by an oblique flame initiated at the beginning of the interaction between the two media. Minimal conditions for detonative combustion are deduced, which correspond to a postshock temperature T{sub s} {approx_equal} 1,000 K, while the minimal condition for combustion as an oblique flame behind the OSW is T{sub s} {approx_equal} 800 K. For CH{sub 4}-air mixtures, no detonation appears even when the degree of overdrive of the theoretically possible solutions of stable ODW is increased up to 1.1 and beyond for T{sub s} up to 1,480 K. Only the OSW and oblique flame configuration are observed. For T{sub s} < 1,000 K, no combustion occurs behind the shock wave. Thus, this mixture appears to be especially difficult to detonate.

  10. Oblique Shock Wave Calculations for Detonation Waves in PBXN-111 Cylindrical Charges Confined in Brass

    NASA Astrophysics Data System (ADS)

    Lemar, E. R.; Forbes, J. W.; Cowperthwaite, M.

    1997-07-01

    Shock polar theory is used to calculate the angle detonation fronts make with brass cases relative to the axis of the PBXN-111 cylinders. It is assumed that no reaction occurs in the detonation front and that the reaction products and brass case remain in contact just behind the shock front. Two extrapolated unreacted Hugoniot curves used in these calculations gave angles of 82 and 84 degrees. Measured angles are between 72 and 75 degrees. The differences between calculated and measured angles are beyond experimental error and suggest that boundary conditions at the explosive/brass interface require more theoretical work.

  11. The evolution and cellular structure of a detonation subsequent to a head-on interaction with a shock wave

    SciTech Connect

    Botros, Barbara B.; Zhu, YuJian; Lee, John H.S.; Ng, Hoi Dick; Ju, Yiguang

    2007-12-15

    This paper analyzes the results of a head-on collision between a detonation and a planar shock wave. The evolution of the detonation cellular structure subsequent to the frontal collision was examined through smoked foil experiments. It is shown that a large reduction in cell size is observed following the frontal collision, and that the detonation cell widths are correlated well with the chemical kinetic calculations from the ZND model. From chemical kinetic calculations, the density increase caused by shock compression appears to be the main factor leading to the significant reduction in cell size. It was found that depending on the initial conditions, the transition to the final cellular pattern can be either smooth or spotty. This phenomenon appears to be equivalent to Oppenheim's strong and mild reflected shock ignition experiments. The difference between these two transitions is, however, more related to the stability of the incident detonation and the strength of the perturbation generated by the incident shock. (author)

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

    NASA Astrophysics Data System (ADS)

    Carvalho, Filipe; Jacinta Soares, Ana

    2012-06-01

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

  13. Reflected Detonation Waves: Comparing Theory to Pressure and Heat Flux Measurements

    NASA Astrophysics Data System (ADS)

    Damazo, J.; Shepherd, J. E.

    Gaseous detonations are of concern to engineers designing piping systems for chemical and nuclear processing facilities. Recently, engineers have also begun to explore the possibility of harnessing the impulse created by detonations for thrust.

  14. Development of detonation reaction engine

    NASA Technical Reports Server (NTRS)

    Lange, O. H.; Stein, R. J.; Tubbs, H. E.

    1968-01-01

    Reaction engine operates on the principle of a controlled condensed detonation. In this engine the gas products that are expelled from the engine to produce thrust are generated by the condensed detonation reaction. The engine is constructed of two basic sections consisting of a detonation wave generator section and a condensed detonation reaction section.

  15. The Effect of Detonation Wave Incidence Angle on the Acceleration of Flyers by Explosives Heavily Laden with Inert Additives

    NASA Astrophysics Data System (ADS)

    Loiseau, Jason; Georges, William; Frost, David; Higgins, Andrew

    2015-06-01

    The incidence angle of a detonation wave is often assumed to weakly influence the terminal velocity of an explosively driven flyer. For explosives heavily loaded with dense additives, this may not be true due to differences in momentum and energy transfer between detonation products, additive particles, and the flyer. For tangential incidence the particles are first accelerated against the flyer via an expansion fan, whereas they are first accelerated by the detonation wave in the normal case. In the current study we evaluate the effect of normal versus tangential incidence on the acceleration of flyers by nitromethane heavily loaded with a variety of additives. Normal detonation was initiated via an explosively driven slapper. Flyer acceleration was measured with heterodyne laser interferometry (PDV). The influence of wave angle is evaluated by comparing the terminal velocity in the two cases (i.e., normal and grazing) for the heavily loaded mixtures. The decrement in flyer velocity correlated primarily with additive volume fraction and had a weak dependence on additive density or particle size. The Gurney energy of the heterogeneous explosive was observed to increase with flyer mass, presumably due to the timescale over which impinging particles could transfer momentum.

  16. Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

    PubMed

    Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

    2016-01-21

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation.

  17. Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

    PubMed

    Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

    2016-01-21

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation. PMID:26688211

  18. Formation of a second shock wave in particle collision with a surface in the course of detonational sputtering

    SciTech Connect

    Buravova, S.N.

    1986-03-01

    This paper elucidates the gasdynamic features of the process of particle collision with a target associated with the formation of a second wave. Approximate solution of the problem of particle impact on a surface leads to the conclusion that the interaction is associated with the formation of a second shock wave (5W) determining the gasdynamic features of the process. The reason for the formation of the second wave is the extremely rapid damping of the SW appearing at the moment of particle collision with the surface. In real conditions of detonational sputtering, the particle is heated by the detonation products to temperatures exceeding 2000/sup 0/C, which makes it plastic and able to spread out over the surface, without which the formation of close contact between the particles and the substrate is impossible.

  19. Detonation Jet Engine. Part 2--Construction Features

    ERIC Educational Resources Information Center

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    We present the most relevant works on jet engine design that utilize thermodynamic cycle of detonative combustion. Detonation engines of various concepts, pulse detonation, rotational and engine with stationary detonation wave, are reviewed. Main trends in detonation engine development are discussed. The most important works that carried out…

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

    SciTech Connect

    Fleming, K.J.

    1993-03-01

    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.

  1. Numerical Optimisation in Non Reacting Conditions of the Injector Geometry for a Continuous Detonation Wave Rocket Engine

    NASA Astrophysics Data System (ADS)

    Gaillard, T.; Davidenko, D.; Dupoirieux, F.

    2015-06-01

    The paper presents the methodology and the results of a numerical study, which is aimed at the investigation and optimisation of different means of fuel and oxidizer injection adapted to rocket engines operating in the rotating detonation mode. As the simulations are achieved at the local scale of a single injection element, only one periodic pattern of the whole geometry can be calculated so that the travelling detonation waves and the associated chemical reactions can not be taken into account. Here, separate injection of fuel and oxidizer is considered because premixed injection is handicapped by the risk of upstream propagation of the detonation wave. Different associations of geometrical periodicity and symmetry are investigated for the injection elements distributed over the injector head. To analyse the injection and mixing processes, a nonreacting 3D flow is simulated using the LES approach. Performance of the studied configurations is analysed using the results on instantaneous and mean flowfields as well as by comparing the mixing efficiency and the total pressure recovery evaluated for different configurations.

  2. Detonation wave velocity and curvature of a plastic-bonded, nonideal explosive PBXN-111 as a function of diameter and confinement

    NASA Astrophysics Data System (ADS)

    Forbes, J. W.; Lemar, E. R.

    1998-12-01

    Detonation velocities and wave front curvatures are measured on various diameter cylinders of PBXN-111 (RDX/AP/Al/HTPB binder with 20/43/25/12 weight percent). The cylinders are either unconfined or encased in 5-mm-thick brass tubes. In all experiments with brass tubes (diameters from 19 to 100 mm) the detonation velocity of PBXN-111 was affected by the confinement. Steady detonation waves propagated in brass encased charges with diameters as small as 19 mm, which is about half of the 37.1 mm failure diameter for unconfined PBXN-111. The radii of curvature at the center of the detonation wave fronts ranged from 52 to 480 mm for charge diameters from 25 to 100 mm, respectively. Detonation velocity as a function of radius of curvature at the wave's center is represented by a single curve for both cased and uncased cylindrical charges. The difference in the axial position of the detonation wave at the center of the charge and at the edge of the charge (i.e., lag distance) are between 1.6 and 6.7 mm. The angles between the detonation wave fronts and the brass/charge interfaces are between 73° and 82° while the angles at the cylindrical free surface for the uncased charges are between 61° and 64°. Calculation of this angle for brass encased charges using oblique shock equations and assuming no reaction in the shock front resulted in angles 8° higher than measured except for the 100-mm-diam charge which was in agreement. The calculated angles for the uncased charge are in agreement with the measured values.

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

    NASA Astrophysics Data System (ADS)

    Krehl, Peter O. K.

    2011-07-01

    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.

  4. On the propagation velocity of a detonation-shock combined wave

    NASA Technical Reports Server (NTRS)

    Tsuge, S.; Fujiwara, T.

    1974-01-01

    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.

  5. Propagation of a detonation shock wave in a gravitating sphere with subsequent expansion into vacuum

    NASA Astrophysics Data System (ADS)

    Golubiatnikov, A. N.; Chilachava, T. I.

    1986-08-01

    The paper is concerned with the non-self-similar problem of a central explosion accompanied by the detonation of a homogeneous gravitating gas sphere. The problem is solved by using the asymptotic method of a thin shock layer proposed by Chernyi (1957) and involving a small parameter. The use of the small parameter makes it possible to describe the expansion of the main mass of the gas into vacuum.

  6. Investigation of Detonation Wave in Tetranitromethane, Nitromethane, and Their Solutions with Methanol

    NASA Astrophysics Data System (ADS)

    Mochalova, V. M.; Utkin, A. V.; Garanin, V. A.

    2010-10-01

    The experimental investigation of reaction zone structure was conducted for steady-state detonation in tetranitromethane (TNM), nitromethane (NM), TNM/methanol (TNM/M), and NM/methanol (NM/M) solutions. A VISAR laser interferometer was used. As the result of measurements, particle velocity profiles with clearly defined Von Neumann spikes were determined. For TNM and NM reaction time, parameters in Von Neumann spike and in Chapman-Jouguet point were determined.

  7. Pulse detonation engines: Technical approaches

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

    The paper contains analysis of the problems preventing from wide use of pulse detonation engines (PDE), and provides suggestions to overcome those problems. In particular, the results of theoretical investigations of basic operating cycle in PDE—deflagration-to-detonation transition (DDT) processes in combustible gaseous mixtures and transmission of detonation into large chambers—are presented. The paper investigates the effect of implosion shock waves on the onset of detonation in gases, and suggests the scheme of detonation transmission from a narrow gap into a wide chamber, which makes it possible to reduce the predetonation length thus shortening the necessary length of the engine.

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

    NASA Astrophysics Data System (ADS)

    Richard, Jacques C.; Myrabo, Leik N.

    2005-04-01

    A detailed parametric study of airbreathing engine performance is carried out for the Lightcraft Technology Demonstrator (LTD), a 1.4-m diameter, 120-kg (dry mass) launch vehicle designed to become a microsatellite after reaching orbit. The LTD's pulsed detonation engine employs repetitively ignited, laser-supported detonation waves to develop thrust by expanding high pressure blast waves over an annular, interior shroud surface. This companion paper presents the analytical LTD airbreathing inlet and vehicle aerodynamics models used to predict basic engine performance and vehicle drag characteristics, including inlet total pressure recovery, captured air mass flow rate, ram drag, etc. — all projected vs. flight Mach number and altitude. The results of this parametric study suggest an optimum inlet air gap of 3-cm for the 100-cm diameter centerbody (external compression inlet), and that Mach 5.5 at 30-km is a reasonable choice for transitioning into the rocket mode.

  9. Optically detonated explosive device

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    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.

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

    SciTech Connect

    Hanjalic, K. . Lehrstuhl fuer Stroemungsmechanik); Smajevic, I. )

    1994-01-01

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

  11. Detonation control

    DOEpatents

    Mace, Jonathan L.; Seitz, Gerald J.; Bronisz, Lawrence E.

    2016-10-25

    Detonation control modules and detonation control circuits are provided herein. A trigger input signal can cause a detonation control module to trigger a detonator. A detonation control module can include a timing circuit, a light-producing diode such as a laser diode, an optically triggered diode, and a high-voltage capacitor. The trigger input signal can activate the timing circuit. The timing circuit can control activation of the light-producing diode. Activation of the light-producing diode illuminates and activates the optically triggered diode. The optically triggered diode can be coupled between the high-voltage capacitor and the detonator. Activation of the optically triggered diode causes a power pulse to be released from the high-voltage capacitor that triggers the detonator.

  12. Theory of gaseous detonations.

    PubMed

    Clavin, Paul

    2004-09-01

    The objective of the present paper is to review some developments that have occurred in detonation theory over the last ten years. They concern nonlinear dynamics of detonation fronts, namely patterns of pulsating and/or cellular fronts, selection of the cell size, dynamical self-quenching, direct (blast) or spontaneous initiation, and transition from deflagration to detonation. These phenomena are all well documented by experiments since the sixties but remained unexplained until recently. In the first part of the paper, the patterns of cellular detonations are described by an asymptotic solution to nonlinear hyperbolic equations (reactive Euler equations) in the form of unsteady (sometime chaotic) and multidimensional traveling-waves. In the second part, turning points of quasi-steady solutions are shown to correspond to critical conditions of fully unsteady problems, either for (direct or spontaneous) initiation or for spontaneous failure (self-quenching). Physical insights are tentatively presented rather than technical aspects. The challenge is to identify the physical mechanisms with their relevant parameters, and more specifically to explain how the length-scales involved in detonation dynamics are larger by two order of magnitude (at least) than the length-scale involved in the steady planar traveling-wave solution (detonation thickness). PMID:15446993

  13. Theory of gaseous detonations.

    PubMed

    Clavin, Paul

    2004-09-01

    The objective of the present paper is to review some developments that have occurred in detonation theory over the last ten years. They concern nonlinear dynamics of detonation fronts, namely patterns of pulsating and/or cellular fronts, selection of the cell size, dynamical self-quenching, direct (blast) or spontaneous initiation, and transition from deflagration to detonation. These phenomena are all well documented by experiments since the sixties but remained unexplained until recently. In the first part of the paper, the patterns of cellular detonations are described by an asymptotic solution to nonlinear hyperbolic equations (reactive Euler equations) in the form of unsteady (sometime chaotic) and multidimensional traveling-waves. In the second part, turning points of quasi-steady solutions are shown to correspond to critical conditions of fully unsteady problems, either for (direct or spontaneous) initiation or for spontaneous failure (self-quenching). Physical insights are tentatively presented rather than technical aspects. The challenge is to identify the physical mechanisms with their relevant parameters, and more specifically to explain how the length-scales involved in detonation dynamics are larger by two order of magnitude (at least) than the length-scale involved in the steady planar traveling-wave solution (detonation thickness).

  14. Bidirectional slapper detonators in spherical explosion systems

    NASA Astrophysics Data System (ADS)

    Martinez, Ernest C.

    1990-11-01

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

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

    SciTech Connect

    Hanjalic, K. ); Smajevic, I. )

    1994-01-01

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

  16. A summary of hydrogen-air detonation experiments

    SciTech Connect

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

    1989-05-01

    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.

  17. Two phase detonation studies conducted in 1971

    NASA Technical Reports Server (NTRS)

    Nicholls, J. A.

    1972-01-01

    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.

  18. Planar Reflection of Gaseous Detonations

    NASA Astrophysics Data System (ADS)

    Damazo, Jason Scott

    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.

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

    SciTech Connect

    Dan, Marius; Rosswog, Stephan; Guillochon, James; Ramirez-Ruiz, Enrico E-mail: rosswog@jacobs-university.de E-mail: enrico@ucolick.org

    2011-08-20

    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.

  20. Influence of sweeping detonation-wave loading on damage evolution during spallation loading of tantalum in both a planar and curved geometry

    SciTech Connect

    Gray, George Thompson III; Hull, Lawrence Mark; Livescu, Veronica; Faulkner, James; Briggs, Matthew E.; Meyer, Ross Keith; Andrews, Heather Lynn; Hare, Steven John; Jakulewicz, Micah Shawn; Shinas, Michael A.

    2015-03-30

    Widespread research over the past five decades has provided a wealth of experimental data and insight concerning the shock hardening, damage evolution, and the spallation response of materials subjected to square-topped shock-wave loading profiles. However, fewer quantitative studies have been conducted on the effect of direct, in-contact, high explosive (HE)-driven Taylor wave (unsupported shocks) loading on the shock hardening, damage evolution, or spallation response of materials. Systematic studies quantifying the effect of sweeping-detonation wave loading are yet sparser. In this study, the damage evolution and spallation response of Ta is shown to be critically dependent on the peak shock stress, the geometry of the sample (flat or curved plate geometry), and the shock obliquity during sweeping-detonation-wave shock loading. Sweepingwave loading in the flat-plate geometry is observed to: a) yield a lower spall strength than previously documented for 1-D supported-shock-wave loading, b) exhibit increased shock hardening as a function of increasing obliquity, and c) lead to an increased incidence of deformation twin formation with increasing shock obliquity. Sweeping-wave loading of a 10 cm radius curved Ta plate is observed to: a) lead to an increase in the shear stress as a function of increasing obliquity, b) display a more developed level of damage evolution, extensive voids and coalescence, and lower spall strength with obliquity in the curved plate than seen in the flat-plate sweeping-detonation wave loading for an equivalent HE loading, and c) no increased propensity for deformation twin formation with increasing obliquity as seen in the flat-plate geometry. The overall observations comparing and contrasting the flat versus curved sweeping-wave spall experiments with 1D loaded spallation behavior suggests a coupled influence of obliquity and geometry on dynamic shock-induced damage evolution and spall strength. Coupled experimental and modeling research

  1. Rotary detonation engine

    SciTech Connect

    Eidelman, S.

    1988-05-03

    In an engine of the type wherein the combustion of the fuel mixture is carried out by a detonation wave, the improvement is described comprising: (a) an elongated shaft having a central longitudinal chamber, the chamber being supplied with a detonatable fuel mixture; (b) axisymmetrical elements integral with the shaft and disposed along the length thereof; (c) means for selectively introducing the detonatable mixture from the central chamber into the initiation chamber of each axisymmetrical element and the ducts of the axisymmetrical element; and (d) means for selectively initiating detonation of the fuel mixture in the initiation chamber of each the axisymmetrical element, whereby ignition and detonation of fuel mixture in the initiation chamber will produce a detonation wave which travels outward from such initiation chamber in the ducts to initiate fast combustion of the fuel mixture in the ducts. The combustion products are exhausted from the exhaust openings in the form of high speed jets oriented to produce a rotational moment in the element and the shaft.

  2. Deflagration to detonation transition in combustible gas mixtures

    SciTech Connect

    Smirnov, N.N.; Panfilov, I.I.

    1995-04-01

    This paper presents the results of a computational investigation of the process of deflagration to detonation transition in a combustible gas mixture. The type of combustion (i.e., deflagration or detonation) supported by a two-step reaction scheme is studied as a function of the activation energies. It is shown that both a deflagration to detonation transition and a deflagration wave that lags behind a leading shock are possible. Two types of deflagration to detonation transitions are found theoretically: initiation of detonation from the flame zone and initiation of detonation along a contact discontinuity in the compressed gas near the primary shock wave.

  3. Detonating apparatus

    DOEpatents

    Johnston, Lawrence H.

    1976-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Richard, Jacques C.; Myrabo, Leik N.

    2005-04-01

    An investigation is performed on an airbreathing laser propulsion (LP) system designed to propel a 1.4 m diameter, 120-kg (dry mass) vehicle called the Lightcraft Technology Demonstrator (LTD) into low Earth orbit, along with its opto-electronics payload. The LTD concept led directly to the model ♯200 lightcraft — recently demonstrated in laboratory and flight experiments at White Sands Missile Range, NM at the High Energy Laser Systems Test Facility (HELSTF), using the 10-kW PLVTS CO2 laser. The pulsed detonation wave engine (PDE) employs repetitively ignited, laser-supported detonation (LSD) waves to develop thrust by expanding high pressure blast waves over an annular, interior shroud surface. Numerical simulation of thruster impulse is accomplished with a 1-D cylindrical model of blast waves propagating radially outward from a laser-generated `line-source' of high temperature, high pressure air. External airflow over the LTD structure is also analyzed to predict basic engine/vehicle drag characteristics, including inlet total pressure recovery, and captured air mass flow rate — all projected vs. flight Mach number and altitude.

  5. Detonation properties of bromonitromethane

    NASA Astrophysics Data System (ADS)

    Davis, Lloyd L.; Sheffield, Stephen A.; Engelke, Ray

    2000-04-01

    Bromonitromethane (CH2BrNO2)(BrNM) is chemically similar to nitromethane (NM), with one hydrogen atom replaced by bromine. It is a liquid explosive with an initial density of 2.009 g/cm3. We have shown its sensitivity to shock to be similar to neat NM. Its von Neumann spike pressure is calculated to be nearly twice that of NM while the CJ pressure appears to be only slightly higher than NM. The sound speed of BrNM was measured to be 1.16 km/s and was used in the Universal Liquid Hugoniot (1). Shock Hugoniot measurements were shown to be consistent with this prediction. In addition, we report the results of failure diameter measurements, and the diameter effect curve in brass confinement. Detonation wave profiles obtained using VISARs that record the interface particle velocity between detonating BrNM and a poly(methyl methacrylate) window are also reported.

  6. Initiation of Gaseous Detonation by Conical Projectiles

    NASA Astrophysics Data System (ADS)

    Verreault, Jimmy

    Initiation and stabilization of detonation by hypersonic conical projectiles launched into combustible gas mixtures is investigated. This phenomenon must be understood for the design and optimization of specific hypersonic propulsion devices, such as the oblique detonation wave engine and the ram accelerator. The criteria for detonation initiation by a projectile is also related to fundamental aspects of detonation research, such as the requirement for direct initiation of a detonation by a blast wave. Experimental results of this problem also offer useful references for validation of numerical and theoretical modeling. Projectiles with cone half angles varying from 15° to 60° were launched into stoichiometric mixtures of hydrogen/oxygen with 70% argon dilution at initial pressures between 10 and 200 kPa. The projectiles were launched from a combustion-driven gas gun at velocities up to 2.2 km/s (corresponding to 133% of the Chapman Jouguet velocity). Pictures of the flowfields generated by the projectiles were taken via Schlieren photography. Five combustion regimes were observed about the projectile ranging from prompt and delayed oblique detonation wave formation, combustion instabilities, a wave splitting, and an inert shock wave. Two types of transition from the prompt oblique detonation wave regime to the inert shock regime were observed. The first (the delayed oblique detonation wave regime) showed an inert shock attached to the tip of the projectile followed by a sharp kink at the onset of an oblique detonation wave; this regime occurred by decreasing the cone angle at high mixture pressures. The second (the combustion instabilities regime) exhibited large density gradients due to combustion ignition and quenching phenomena; this regime occurred by decreasing the mixture pressure at large cone angles. A number of theoretical models were considered to predict critical conditions for the initiation of oblique detonations. The Lee-Vasiljev model agreed

  7. Detonation Properties and Thermal Behavior of FOX-7-Based Explosives

    NASA Astrophysics Data System (ADS)

    Trzciński, W. A.; Cudziło, S.; Chyłek, Z.; Szymańczyk, L.

    2013-01-01

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

  8. Detonation Properties of Bromonitromethane

    NASA Astrophysics Data System (ADS)

    Davis, Lloyd L.; Sheffield, Stephen A.; Engelke, Ray

    1999-06-01

    Bromonitromethane (CH_2BrNO_2)(BrNM) is chemically similar to nitromethane (NM), with one hydrogen atom replaced by bromine. It is a liquid explosive with an initial density of 2.009 g/cm^3. We have shown its sensitivity to shock to be similar to neat NM. However, its performance (CJ pressure) appears to be about twice that of NM. The sound speed of BrNM was measured to be 1.16 km/s and was used in the Universal Liquid Hugoniot (R. W. Woolfolk, M. Cowperthwaite and R. Shaw, Thermochimica Acta, 5), 409 (1983). to predict the unreacted Hugoniot. Shock Hugoniot measurements were shown to be consistent with this prediction. In addition, we report the BrNM detonation velocity, failure diameter in brass, and diameter effect curve. Detonation wave profiles obtained using VISAR to record the interface particle velocity between the detonating BrNM and a polymethyl methacrylate (PMMA) window have also been measured. There are interesting features in these measurements that may provide information about the reactions occurring in the BrNM and/or the effect of the confinement.

  9. Cellular structure of detonation utilized in propulsion system

    NASA Astrophysics Data System (ADS)

    Zhang, XuDong; Fan, BaoChun; Gui, MingYue; Pan, ZhenHua

    2012-10-01

    How to confine a detonation in a combustor is a key issue of detonation applications in propulsion systems. Based on achieving schemes, detonations applied in the combustor, including pulse detonation wave (PDW), oblique detonation wave (ODW) and rotating detonation wave (RDW), are different from that described by the classic CJ theory in fine structures and its self-sustaining mechanisms. In this work, the cellular structures and flow fields of ODW and RDW were obtained numerically, and the fundamental characteristics and self-sustaining mechanisms of the detonations were analyzed and discussed. ODW front consists of three parts: the ZND-like front, the single-headed triple point front and the dual-headed triple point front. Cellular structures of RDW are heterogeneous, and the cell size near the outer wall is smaller than that near the inner wall.

  10. Numerical simulation of spinning detonation in circular section channels

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    Numerical simulation of three-dimensional structures of gas detonation in circular section channels that emerge due to the instability when the one-dimensional flow is initiated by energy supply at the closed end of the channel is performed. It is found that in channels with a large diameter, an irregular three-dimensional cellular detonation structure is formed. Furthermore, it is found that in channels with a small diameter circular section, the initially plane detonation wave is spontaneously transformed into a spinning detonation wave, while passing through four phases. A critical value of the channel diameter that divides the regimes with the three-dimensional cellular detonation and spinning detonation is determined. The stability of the spinning detonation wave under perturbations occurring when the wave passes into a channel with a greater (a smaller) diameter is investigated. It is found that the spin is preserved if the diameter of the next channel (into which the wave passes) is smaller (respectively, greater) than a certain critical value. The computations were performed on the Lomonosov supercomputer using from 0.1 to 10 billions of computational cells. All the computations of the cellular and spinning detonation were performed in the whole long three-dimensional channel (up to 1 m long) rather than only in its part containing the detonation wave; this made it possible to adequately simulate and investigate the features of the transformation of the detonation structure in the process of its propagation.

  11. Initiation of the Detonation in the Gravitationally Confined Detonation Model of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

    We study the initiation of the detonation in the gravitationally confined detonation (GCD) model of Type Ia supernovae (SNe Ia). In this model, ignition occurs at one or several off-center points, resulting in a burning bubble of hot ash that rises rapidly, breaks through the surface of the star, and collides at a point on the stellar surface opposite the breakout, producing a high-velocity inwardly directed flow. Initiation of the detonation occurs spontaneously in a region where the length scale of the temperature gradient extending from the flow (in which carbon burning is already occurring) into unburned fuel is commensurate to the range of critical length scales which have been derived from one-dimensional simulations that resolve the initiation of a detonation. By increasing the maximum resolution in a truncated cone that encompasses this region, beginning somewhat before initiation of the detonation occurs, we successfully simulate in situ the first gradient-initiated detonation in a whole-star simulation. The detonation emerges when a compression wave overruns a pocket of fuel situated in a Kelvin-Helmholtz cusp at the leading edge of the inwardly directed jet of burning carbon. The compression wave preconditions the temperature in the fuel in such a way that the Zel'dovich gradient mechanism can operate and a detonation ensues. We explore the dependence of the length scale of the temperature gradient on spatial resolution and discuss the implications for the robustness of this detonation mechanism. We find that the time and the location at which initiation of the detonation occurs varies with resolution. In particular, initiation of a detonation had not yet occurred in our highest resolution simulation by the time we ended the simulation because of the computational demand it required. However, it may detonate later. We suggest that the turbulent shear layer surrounding the inwardly directed jet provides the most favorable physical conditions, and

  12. Effect of Aluminium Confinement on ANFO Detonation

    NASA Astrophysics Data System (ADS)

    Short, Mark; Jackson, Scott; Kiyanda, Charles; Shinas, Mike; Hare, Steve; Briggs, Matt

    2013-06-01

    Detonations in confined non-ideal high explosives often have velocities below the confiner sound speed. The effect on detonation propagation of the resulting subsonic flow in the confiner (such as confiner stress waves traveling ahead of the main detonation front or upstream wall deflection into the HE) has yet to be fully understood. Previous work by Sharpe and Bdzil (J. Eng. Math, 2006) has shown that for subsonic confiner flow, there is no limiting thickness for which the detonation dynamics are uninfluenced by further increases in wall thickness. The critical parameters influencing detonation behavior are the wall thickness relative to the HE reaction zone size, and the difference in the detonation velocity and confiner sound speed. Additional possible outcomes of subsonic flow are that for increasing thickness, the confiner is increasingly deflected into the HE upstream of the detonation, and that for sufficiently thick confiners, the detonation speed could be driven up to the sound speed in the confiner. We report here on a further series of experiments in which a mixture of ammonium nitrate and fuel oil (ANFO) is detonated in aluminum confiners with varying HE charge diameter and confiner thickness, and compare the results with the outcomes suggested by Sharpe and Bdzil.

  13. Detonation duct gas generator demonstration program

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  14. Impulse generation by detonation tubes

    NASA Astrophysics Data System (ADS)

    Cooper, Marcia Ann

    partially filled detonation tubes was compiled and analyzed with models investigating concepts of energy conservation and unsteady gas dynamics. A model to predict the specific impulse was developed for partially filled tubes. The role of finite chemical kinetics in detonation products was examined through numerical simulations of the flow in nonsteady expansion waves.

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

    NASA Astrophysics Data System (ADS)

    Yan, Yu; Fan, Wei; Mu, Yang

    2012-12-01

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

  16. Demonstration of a multi-channel, low-profile wire gauge for tracing wave development and detonation turning in explosives

    SciTech Connect

    Skidmore, Bradley E; Novak, Alan M; Zucker, Jonathan M; Parker, Jr, Gary R; Dickson, Peter; Foley, Timothy J; Trebs, Adam A

    2010-01-01

    The multi-channel low-profile wire gauge is a device which measures high pressure wave position via the continuous variation in length of a conductor in conjunction with a fiducial, allowing in situ measurement of wave front curvature during wave development. The gauge's low profile ({approx}250 {micro}m) and high resolution measurements (up to 0.5 nanoseconds) make it minimally intrusive and highly responsive, with a typically wave position accuracy of {+-}1 mm. Gauge construction and data analysis methods are described and waveforms are presented for Detasheet and N-9 explosives.

  17. Autoignitions and detonations in engines and ducts.

    PubMed

    Bradley, Derek

    2012-02-13

    The origins of autoignition at hot spots are analysed and the pressure pulses that arise from them are related to knock in gasoline engines and to developing detonations in ducts. In controlled autoignition engines, autoignition is benign with little knock. There are several modes of autoignition and the existence of an operational peninsula, within which detonations can develop at a hot spot, helps to explain the performance of various engines. Earlier studies by Urtiew and Oppenheim of the development of autoignitions and detonations ahead of a deflagration in ducts are interpreted further, using a simple one-dimensional theory of the generation of shock waves ahead of a turbulent flame. The theory is able to indicate entry into the domain of autoignition in an 'explosion in the explosion'. Importantly, it shows the influence of the turbulent burning velocity, and particularly its maximum attainable value, upon autoignition. This value is governed by localized flame extinctions for both turbulent and laminar flames. The theory cannot show any details of the transition to a detonation, but regimes of eventually stable or unstable detonations can be identified on the operational peninsula. Both regimes exhibit transverse waves, triple points and a cellular structure. In the case of unstable detonations, transverse waves are essential to the continuing propagation. For hazard assessment, more needs to be known about the survival, or otherwise, of detonations that emerge from a duct into the same mixture at atmospheric pressure. PMID:22213665

  18. Autoignitions and detonations in engines and ducts.

    PubMed

    Bradley, Derek

    2012-02-13

    The origins of autoignition at hot spots are analysed and the pressure pulses that arise from them are related to knock in gasoline engines and to developing detonations in ducts. In controlled autoignition engines, autoignition is benign with little knock. There are several modes of autoignition and the existence of an operational peninsula, within which detonations can develop at a hot spot, helps to explain the performance of various engines. Earlier studies by Urtiew and Oppenheim of the development of autoignitions and detonations ahead of a deflagration in ducts are interpreted further, using a simple one-dimensional theory of the generation of shock waves ahead of a turbulent flame. The theory is able to indicate entry into the domain of autoignition in an 'explosion in the explosion'. Importantly, it shows the influence of the turbulent burning velocity, and particularly its maximum attainable value, upon autoignition. This value is governed by localized flame extinctions for both turbulent and laminar flames. The theory cannot show any details of the transition to a detonation, but regimes of eventually stable or unstable detonations can be identified on the operational peninsula. Both regimes exhibit transverse waves, triple points and a cellular structure. In the case of unstable detonations, transverse waves are essential to the continuing propagation. For hazard assessment, more needs to be known about the survival, or otherwise, of detonations that emerge from a duct into the same mixture at atmospheric pressure.

  19. Simple detonation meter

    NASA Astrophysics Data System (ADS)

    Sukhov, N.

    1985-01-01

    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.

  20. Internal Detonation Velocity Measurements Inside High Explosives

    SciTech Connect

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

    2009-01-16

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

  1. Detonation interaction with an interface

    NASA Astrophysics Data System (ADS)

    Lieberman, D. H.; Shepherd, J. E.

    2007-09-01

    Detonation interaction with an interface was investigated, where the interface separated a combustible from an oxidizing or inert mixture. The ethylene-oxygen combustible mixture had a fuel-rich composition to promote secondary combustion with the oxidizer in the turbulent mixing zone (TMZ) that resulted from the interaction. Sharp interfaces were created by using a nitro-cellulose membrane to separate the two mixtures. The membrane was mounted on a wood frame and inserted in the experimental test section at a 45° angle to the bulk flow direction. The membrane was destroyed by the detonation wave. The interaction resulted in a transmitted and reflected wave at a node point similar to regular shock refraction. A detonation refraction analysis was carried out to compare with the measured shock angles. It was observed that the measured angle is consistently lower than the predicted value. An uncertainty analysis revealed possible explanations for this systematic variation pointing to factors such as the incident wave curvature and the role of the nitro-cellulose diaphragm. Analysis of the TMZ and Mach stem formed from the reflection of the transmitted shock wave off the solid boundary were carried out and found to justify the size and strength of these features as a function of the test gas composition. The role of secondary combustion in the TMZ was also investigated and found to have a small influence on the wave structure.

  2. 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

    Deiterding, Ralf

    2011-01-01

    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.

  3. High-Resolution Numerical Simulation and Analysis of Mach Reflection Structures in Detonation Waves in Low-Pressure H 2 –O 2 –Ar Mixtures: A Summary of Results Obtained with the Adaptive Mesh Refinement Framework AMROC

    DOE PAGES

    Deiterding, Ralf

    2011-01-01

    Numerical simulation can be key to the understanding of the multidimensional 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 nonequilibrium 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 techniquesmore » in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, 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.« less

  4. Effect of Detonation through a Turbine Stage

    NASA Technical Reports Server (NTRS)

    Ellis, Matthew T.

    2004-01-01

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

  5. The influence of detonation cell size and regularity on the propagation of gaseous detonations in granular materials

    NASA Astrophysics Data System (ADS)

    Slungaard, T.; Engebretsen, T.; Sønju, O. K.

    This paper presents results from an experimental study of transmission of gaseous detonation waves through various granular filters. Spherical glass beads of 4 and 8 mm diameter and crushed rock of 7.5 mm volume averaged diameter were used as filter material. Varying the initial pressure of the detonating gas mixture controlled the detonation cell size. Dilution with argon was used to vary the detonation cell regularity. The complete range from almost no detonation velocity deficit to complete extinction of the combustion wave was observed. The existing correlation for gaseous detonation velocity deficit V/VCJ = [1-0.35 (d_ c/dps)] +/- 0.1 where dc is the critical diameter for the gaseous detonation and dps is the pore size, is found to be applicable for both smooth spherical particles and irregular crushed rock when considering irregular detonation structures. Soot films and pressure measurements show that as the detonation cell size is increased, reinitiation of a reanular filter until it finally no longer occurs at V/VCJ ~ 0.4--0.45. Complete extinction of the combustion wave occurs at V/VCJ ~ 0.25--0.3. These two limits appear to be about the same for irregular and regular detonation cell structures. For irregular structures without argon dilution, dc/dps ~ 50 can be found for detonation wave failure, and dc/dps ~ 100 can be found for complete extinction of the combustion wave. For argon dilution these limits are changed to dc/dps ~ 10 and dc/dps ~ 40, respectively. The data are a bit scarce as a basis for proposing a new correlation for regular structures, but as a first approximation V/VCJ =[0.8--0.35log(dc/dps)] +/- 0.1 is suggested for regular structures. The detonation or combustion wave is found to approach a constant velocity in the granular filter if not extinguished.

  6. Continuous detonation reaction engine

    NASA Technical Reports Server (NTRS)

    Lange, O. H.; Stein, R. J.; Tubbs, H. E.

    1968-01-01

    Reaction engine operates on the principles of a controlled condensed detonation rather than on the principles of gas expansion. The detonation results in reaction products that are expelled at a much higher velocity.

  7. Methods for proving the equivalency of detonator performance

    SciTech Connect

    Munger, Alan C; Akinci, Adrian A; Thomas, Keith A; Clarke, Steve A; Martin, Eric S; Murphy, Michael J

    2009-01-01

    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.

  8. Effects of high sound speed confiners on ANFO detonations

    NASA Astrophysics Data System (ADS)

    Kiyanda, Charles; Jackson, Scott; Short, Mark

    2011-06-01

    The interaction between high explosive (HE) detonations and high sound speed confiners, where the confiner sound speed exceeds the HE's detonation speed, has not been thoroughly studied. The subsonic nature of the flow in the confiner allows stress waves to travel ahead of the main detonation front and influence the upstream HE state. The interaction between the detonation wave and the confiner is also no longer a local interaction, so that the confiner thickness now plays a significant role in the detonation dynamics. We report here on larger scale experiments in which a mixture of ammonium nitrate and fuel oil (ANFO) is detonated in aluminium confiners with varying charge diameter and confiner thickness. The results of these large-scale experiments are compared with previous large-scale ANFO experiments in cardboard, as well as smaller-scale aluminium confined ANFO experiments, to characterize the effects of confiner thickness.

  9. The Physical Effects of Detonation in a Closed Cylindrical Chamber

    NASA Technical Reports Server (NTRS)

    Draper, C S

    1935-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Rohit Ranjan

    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

  11. High temperature detonator

    DOEpatents

    Johnson, James O.; Dinegar, Robert H.

    1988-01-01

    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.

  12. Molecular-dynamics investigation of the desensitization of detonable material

    NASA Astrophysics Data System (ADS)

    Rice, Betsy M.; Mattson, William; Trevino, Samuel F.

    1998-05-01

    A molecular-dynamics investigation of the effects of a diluent on the detonation of a model crystalline explosive is presented. The diluent, a heavy material that cannot exothermally react with any species of the system, is inserted into the crystalline explosive in two ways. The first series of simulations investigates the attenuation of the energy of a detonation wave in a pure explosive after it encounters a small layer of crystalline diluent that has been inserted into the lattice of the pure explosive. After the shock wave has traversed the diluent layer, it reenters the pure explosive. Unsupported detonation is not reestablished unless the energy of the detonation wave exceeds a threshold value. The second series of simulations investigates detonation of solid solutions of different concentrations of the explosive and diluent. For both types of simulations, the key to reestablishing or reaching unsupported detonation is the attainment of a critical number density behind the shock front. Once this critical density is reached, the explosive molecules make a transition to an atomic phase. This is the first step in the reaction mechanism that leads to the heat release that sustains the detonation. The reactive fragments formed from the atomization of the heteronuclear reactants subsequently combine with new partners, with homonuclear product formation exothermally favored. The results of detonation of the explosive-diluent crystals are consistent with those presented in an earlier study on detonation of pure explosive [B. M. Rice, W. Mattson, J. Grosh, and S. F. Trevino, Phys. Rev. E 53, 611 (1996)].

  13. Stability Affects of Artificial Viscosity in Detonation Modeling

    SciTech Connect

    Vitello, P; Souers, P C

    2002-06-03

    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.

  14. Modelling detonation of heterogeneous explosives with embedded inert particles using detonation shock dynamics: Normal and divergent propagation in regular and simplified microstructure

    NASA Astrophysics Data System (ADS)

    Lieberthal, Brandon A.; Bdzil, John B.; Stewart, D. Scott

    2014-03-01

    This paper discusses the mathematical formulation of Detonation Shock Dynamics (DSD) regarding a detonation shock wave passing over a series of inert spherical particles embedded in a high-explosive material. DSD provides an efficient method for studying detonation front propagation in such materials without the necessity of simulating the combustion equations for the entire system. We derive a series of partial differential equations in a cylindrical coordinate system and a moving shock-attached coordinate system which describes the propagation of detonation about a single particle, where the detonation obeys a linear shock normal velocity-curvature (Dn-κ) DSD relation. We solve these equations numerically and observe the short-term and long-term behaviour of the detonation shock wave as it passes over the particles. We discuss the shape of the perturbed shock wave and demonstrate the periodic and convergent behaviour obtained when detonation passes over a regular, periodic array of inert spherical particles.

  15. Detonation duct gas generator demonstration program

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  16. Computation of a diverging Comp-B detonation

    SciTech Connect

    Bukiet, B.G.

    1989-01-01

    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.

  17. Cellular detonation diffraction in gas-particle mixtures

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Khmel, T. A.; Kratova, Y. V.

    2010-12-01

    Diffraction of cellular heterogeneous detonation out of a channel into open half-space in a mixture of aluminum particles and oxygen is investigated numerically. The flow is found to be very similar to gas detonation diffraction. The detonation weakening behind the step results in combustion front deceleration and decoupling from the leading shock wave. Subsequent re-initiation takes place in a transverse wave. New transverse waves are generated along the expanding front. The computations that were performed show that the critical number of cells is several times less than that for gases. This is confirmed by theoretical estimates based upon the Mitrofanov-Soloukhin approach.

  18. Detonation diffraction from an annular channel

    NASA Astrophysics Data System (ADS)

    Meredith, James; Ng, Hoi Dick; Lee, John H. S.

    2010-12-01

    In this study, gaseous detonation diffraction from an annular channel was investigated with a streak camera and the critical pressure for transmission of the detonation wave was obtained. The annular channel was used to approximate an infinite slot resulting in cylindrically expanding detonation waves. Two mixtures, stoichiometric acetylene-oxygen and stoichiometric acetylene-oxygen with 70% Ar dilution, were tested in a 4.3 and 14.3 mm channel width ( W). The undiluted and diluted mixtures were found to have values of the critical channel width over the cell size around 3 and 12 respectively. Comparing these results to values of the critical diameter ( d c ), in which a spherical detonation occurs, a value of critical d c / W c near 2 is observed for the highly diluted mixture. This value corresponds to the geometrical factor of the curvature term between a spherical and cylindrical diverging wave. Hence, the result is in support of Lee's proposed mechanism [Lee in Dynamics of Exothermicity, pp. 321, Gordon and Breach, Amsterdam, 1996] for failure due to diffraction based on curvature in stable mixtures such as those highly argon diluted with very regular detonation cellular patterns.

  19. Explosive Products EOS: Adjustment for detonation speed and energy release

    SciTech Connect

    Menikoff, Ralph

    2014-09-05

    Propagating detonation waves exhibit a curvature effect in which the detonation speed decreases with increasing front curvature. The curvature effect is due to the width of the wave profile. Numerically, the wave profile depends on resolution. With coarse resolution, the wave width is too large and results in a curvature effect that is too large. Consequently, the detonation speed decreases as the cell size is increased. We propose a modification to the products equation of state (EOS) to compensate for the effect of numerical resolution; i.e., to increase the CJ pressure in order that a simulation propagates a detonation wave with a speed that is on average correct. The EOS modification also adjusts the release isentrope to correct the energy release.

  20. Numerical simulation of spinning detonation in square tube

    NASA Astrophysics Data System (ADS)

    Tsuboi, Nobuyuki; Asahara, Makoto; Eto, Keitaro; Hayashi, A. Koichi

    2008-09-01

    A single spinning detonation wave propagating in a square tube is simulated three-dimensionally with the detailed chemical reaction mechanism for hydrogen/air mixture proposed by Petersen and Hanson. The spinning detonation is composed of a transverse detonation rotating around the wall normal to the tube axis, triple lines propagating partially out of phase, and a short pressure trail. The formation of an unburned gas pocket behind the detonation front was not observed in the present simulations because the rotating transverse detonation completely consumed the unburned gas. The calculated profiles of instantaneous OH mass fraction have a keystone shape behind the detonation front. The numerical results for the pitch and track angle on the tube wall agree well with the experimental results.

  1. Detonation command and control

    SciTech Connect

    Mace, Jonathan L.; Seitz, Gerald J.; Echave, John A.; Le Bas, Pierre-Yves

    2015-11-10

    The detonation of one or more explosive charges and propellant charges by a detonator in response to a fire control signal from a command and control system comprised of a command center and instrumentation center with a communications link therebetween. The fire control signal is selectively provided to the detonator from the instrumentation center if plural detonation control switches at the command center are in a fire authorization status, and instruments, and one or more interlocks, if included, are in a ready for firing status. The instrumentation and command centers are desirably mobile, such as being respective vehicles.

  2. Detonation command and control

    DOEpatents

    Mace, Jonathan L.; Seitz, Gerald J.; Echave, John A.; Le Bas, Pierre-Yves

    2016-05-31

    The detonation of one or more explosive charges and propellant charges by a detonator in response to a fire control signal from a command and control system comprised of a command center and instrumentation center with a communications link there between. The fire control signal is selectively provided to the detonator from the instrumentation center if plural detonation control switches at the command center are in a fire authorization status, and instruments, and one or more interlocks, if included, are in a ready for firing status. The instrumentation and command centers are desirably mobile, such as being respective vehicles.

  3. Prechamber initiation of detonation in gaseous mixtures

    NASA Astrophysics Data System (ADS)

    Bivol, G. Yu; Golovastov, S. V.; Golub, V. V.

    2015-11-01

    A process of deflagration-to-detonation transition in propane-butane-oxygen and acetylene-oxygen mixtures, in an open channel with a circular cross section with a diameter of 3 mm, was investigated experimentally. Detonation initiation was carried out by burning the mixture in the prechamber connected to the channel. The prechamber was considered as an extended source for the initiation of the detonation of a finite volume. To measure the velocity of a flame front, photodiodes, installed along the axis of the channel, were used. To determine the boundary conditions at the entrance to the channel, a piezoelectric pressure transducer was used. The influence of the dimensions of the prechamber, equivalence ratio and fuel on the pressure profile, and evolution of the flame front along the axis of the channel are presented. It was shown that, the dynamics of the flame front and shock waves in the channel can occur in different scenarios depending on the geometry of the prechamber and equivalence ratio. Two limit effects of the prechamber detonation initiation in the channel have been analyzed. The pre-detonation distances and the minimal energy of direct initiation of the detonation were determined.

  4. Simplified modeling of transition to detonation in porous energetic materials

    NASA Astrophysics Data System (ADS)

    Stewart, D. Scott; Asay, Blaine W.; Prasad, Kuldeep

    1994-07-01

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

  5. Simplified modeling of transition to detonation in porous energetic materials

    SciTech Connect

    Stewart, D.S. ); Asay, B.W. ); Prasad, K. )

    1994-07-01

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

  6. Behavior of detonation propagation in mixtures with concentration gradients

    NASA Astrophysics Data System (ADS)

    Hall, Brian C.; Kirwin, William D.

    2007-08-01

    Behavior of detonation waves in mixtures with concentration gradients normal to the propagation direction was studied experimentally. Mixtures with various concentration gradients were formed by sliding the separation plate which divides a detonation chamber from a diffusion chamber in which a diffusion gas was initially introduced. A stoichiometric hydrogen oxygen mixture was charged in the detonation chamber, while oxygen or nitrogen was filled in the diffusion gas chamber. Temporal concentration measurement was conducted by the infrared absorption method using ethane as alternate of oxygen. Smoked foil records show a deformation of regular diamond cells to parallelogram ones, which well corresponds to local mixture concentration. Schlieren photographs reveal the tilted wave front whose angle is consistent with the deflection angle of the detonation front obtained from trajectories of the triple point. The local deflection angle increases with increase in local concentration gradient. Calculation of wave trajectory based on the ray tracing theory predicts formation of the tilted wave front from an initial planar front.

  7. Bidirectional slapper detonator

    DOEpatents

    McCormick, Robert N.; Boyd, Melissa D.

    1984-01-01

    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.

  8. Exploding bridgewire detonator simulator

    NASA Technical Reports Server (NTRS)

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

    1969-01-01

    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.

  9. The development of a sonic boom simulator with detonable gases

    NASA Technical Reports Server (NTRS)

    Strugielski, R. T.; Fugelso, L. E.; Holmes, L. B.; Byrne, W. J.

    1971-01-01

    A sonic boom pressure profile was simulated in the far-field by detonation of a methane-oxygen mixture contained in a slender, shaped Mylar envelope. Ideal N-waves were synthesized with peak overpressures from two to five psf and durations of 30 to 75 milliseconds. The detonation of the gas mixture was initiated by a single Primacord strand running the length of balloon. The N-wave producing balloon was synthesized as a composite structure, utilizing experimental pressure profiles obtained from the detonations of slender, axisymmetric balloons with elementary, non-cylindrical shapes.

  10. Propagation Mechanism of Cylindrical Cellular Detonation

    NASA Astrophysics Data System (ADS)

    Han, Wen-Hu; Wang, Cheng; Ning, Jian-Guo

    2012-10-01

    We investigate the evolution of cylindrical cellular detonation with different instabilities. The numerical results show that with decreasing initial temperature, detonation becomes more unstable and the cells of the cylindrical detonation tend to be irregular. For stable detonation, a divergence of cylindrical detonation cells is formed eventually due to detonation instability resulting from a curved detonation front. For mildly unstable detonation, local overdriven detonation occurs. The detonation cell diverges and its size decreases. For highly unstable detonation, locally driven detonation is more obvious and the front is highly wrinkled. As a result, the diverging cylindrical detonation cell becomes highly irregular.

  11. Pulse Detonation Engine Test Bed Developed

    NASA Technical Reports Server (NTRS)

    Breisacher, Kevin J.

    2002-01-01

    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.

  12. Numerical simulation of Mach reflection of cellular detonations

    NASA Astrophysics Data System (ADS)

    Li, J.; Lee, J. H. S.

    2016-07-01

    The Mach reflection of cellular detonation waves on a wedge is investigated numerically in an attempt to elucidate the effect of cellular instabilities on Mach reflection, the dependence of self-similarity on the thickness of a detonation wave, and the initial development of the Mach stem near the wedge apex. A two-step chain-branching reaction model is used to give a thermally neutral induction zone followed by a chemical reaction zone for the detonation wave. A sufficiently large distance of travel of the Mach stem is computed to observe the asymptotic behavior in the far field. Depending on the scale at which the Mach reflection process occurs, it is found that the Mach reflection of a cellular detonation behaves essentially in the same way as a planar ZND detonation wave. The cellular instabilities, however, cause the triple-point trajectory to fluctuate. The fluctuations are due to interactions of the triple point of the Mach stem with the transverse waves of cellular instabilities. In the vicinity of the wedge apex, the Mach reflection is found to be self-similar and corresponds to that of a shock wave of the same strength, since the Mach stem is highly overdriven initially. In the far field, the triple-point trajectory approaches a straight line, indicating that the Mach reflection becomes self-similar asymptotically. The distance of the approach to self-similarity is found to decrease rapidly with decreasing thickness of the detonation front.

  13. Numerical simulation of Mach reflection of cellular detonations

    NASA Astrophysics Data System (ADS)

    Li, J.; Lee, J. H. S.

    2016-09-01

    The Mach reflection of cellular detonation waves on a wedge is investigated numerically in an attempt to elucidate the effect of cellular instabilities on Mach reflection, the dependence of self-similarity on the thickness of a detonation wave, and the initial development of the Mach stem near the wedge apex. A two-step chain-branching reaction model is used to give a thermally neutral induction zone followed by a chemical reaction zone for the detonation wave. A sufficiently large distance of travel of the Mach stem is computed to observe the asymptotic behavior in the far field. Depending on the scale at which the Mach reflection process occurs, it is found that the Mach reflection of a cellular detonation behaves essentially in the same way as a planar ZND detonation wave. The cellular instabilities, however, cause the triple-point trajectory to fluctuate. The fluctuations are due to interactions of the triple point of the Mach stem with the transverse waves of cellular instabilities. In the vicinity of the wedge apex, the Mach reflection is found to be self-similar and corresponds to that of a shock wave of the same strength, since the Mach stem is highly overdriven initially. In the far field, the triple-point trajectory approaches a straight line, indicating that the Mach reflection becomes self-similar asymptotically. The distance of the approach to self-similarity is found to decrease rapidly with decreasing thickness of the detonation front.

  14. Detonation Front Curvatures and Detonation Rates

    NASA Astrophysics Data System (ADS)

    Lauderbach, Lisa M.; Lorenz, K. Thomas; Lee, Edward L.; Souers, P. Clark

    2015-06-01

    We have normalized the LLNL library of detonation front curvatures by dividing lags by the edge lag and radii by the edge radius. We then fit the normalized data to the equation L = AR2 + BR8, where L is the normalized lag and R is the normalized radius. We attribute the quadratic term to thermal processes and the 8th-power term to shock processes. We compare the % of the quadratic term J at the edge with detonation rates obtained from the size effect. One class of results is made up of fine-grained, uniform explosives with large lags, where a low detonation rate leads to a high J and vice versa. This provides a rough way of estimating unknown rates if the unknown explosive is of high quality. The other, equally-large class contains rough-grained materials, often with small lags and small radii. These have curves that do not fit the equation but superfically often look quadratic. Some HMX and PETN curvatures even show a ``sombrero'' effect. Code models show that density differences of 0.03 g/cc in ram-pressed parts can cause pseudo-quadratic curves and even sombreros. Modeling is used to illustrate J at the lowest and highest possible detonation rates. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

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

    NASA Astrophysics Data System (ADS)

    Baudin, Gerard

    2005-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

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

  17. Detonation propagation in a high loss configuration

    SciTech Connect

    Jackson, Scott I; Shepherd, Joseph E

    2009-01-01

    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.

  18. Maximum Entropy Theory of Non-Ideal Detonation

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    According to the theory of Byers Brown, in a steady state detonation the entropy production between the shock and sonic locus is a maximum in a self-sustaining wave. This has shown to hold true for all one-dimensional cases. Byers Brown also suggested a novel variational approach by maximising the global entropy generation within the detonation driving zone to solve the problem of self-sustaining, two-dimensional steady curved detonation waves in a slab or cylindrical stick of explosive. Preliminary application of such a variational technique, albeit with simplifying assumptions, demonstrate its potential to provide a rapid and accurate solution method for the problem. In this paper, recent progress in the development and validation of the variational maximum entropy concept, for the case of weakly curved waves, are reported. The predictions of the theory are compared with those of Detonation Shock Dynamics theory.

  19. Ignition and Growth Reactive Flow Modeling of Recent HMX/TATB Detonation Experiments

    NASA Astrophysics Data System (ADS)

    Tarver, Craig

    2015-06-01

    Ignition and Growth model parameters for detonating PBX 9501 (95%HMX, 2.5 %Estane, 2.5%BDNPAF) and PBX 9502 (95%TATB, 5%Kel-F800) are used to simulate two experiments in which detonating HMX-based PBX's accelerate slower detonating TATB PBX's. The measured HMX and TATB detonation velocities, the angles produced in the detonating TATB charges by the leading HMX detonation waves, the arrival times of the complex detonation wave front, and the PDV records measured at several positions along the interfaces between the two explosives and LiF windows are accurately calculated. This work was performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  20. Modeling Hemispheric Detonation Experiments in 2-Dimensions

    SciTech Connect

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

    2006-06-22

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

  1. Measuring In-Situ Mdf Velocity Of Detonation

    DOEpatents

    Horine, Frank M.; James, Jr., Forrest B.

    2005-10-25

    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.

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

    SciTech Connect

    Kerley, G.I.

    1994-05-01

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

  3. Phase detonated shock tube (PFST)

    SciTech Connect

    Zerwekh, W.D.; Marsh, S.P.; Tan, Tai-Ho

    1993-07-01

    The simple, cylindrically imploding and axially driven fast shock tube (FST) has been a basic component in the high velocity penetrator (HVP) program. It is a powerful device capable of delivering a directed and very high pressure output that has been successfully employed to drive hypervelocity projectiles. The FST is configured from a hollow, high-explosive (HE) cylinder, a low-density Styrofoam core, and a one-point initiator at one end. A Mach stem is formed in the core as the forward-propagating, HE detonation wave intersects the reflected radial wave. This simple FST has been found to be a powerful pressure multiplier. Up to 1-Mbar output pressure can be obtained from this device. Further increase in the output pressure can be achieved by increasing the HE detonation velocity. The FST has been fine tuned to drive a thin plate to very high velocity under an impulse per unit area of about 1 Mbar{mu}s/cm{sup 2}. A 1.5-mm-thick stainless steel disk has been accelerated intact to 0.8 cm/{mu}s under a loading pressure rate of several Mbar/{mu}s. By making the plate curvature slightly convex at the loading side the authors have successfully accelerated it to almost 1.0 cm/{mu}s. The incorporation of a barrel at the end of the FST has been found to be important as confinement of the propellant gas by the barrel tends to accelerate the projectile to higher velocity. The desire to accelerate the plate above 1.0 cm/{mu}s provided the impetus to develop a more advanced fast shock tube to deliver a much higher output pressure. This report describes the investigation of a relatively simple air-lens phase-detonation system (PFST) with fifty percent higher phase-detonation velocity and a modest 2 Mbar output. Code calculations have shown that this PFST acceleration of a plate to about 1.2 cm/{mu}s can be achieved. The performance of these PFSTs has been evaluated and the details are discussed.

  4. Phase detonated shock tube (PFST)

    SciTech Connect

    Zerwekh, W.D.; Marsh, S.P.; Tan, Tai-Ho.

    1993-01-01

    The simple, cylindrically imploding and axially driven fast shock tube (FST) has been a basic component in the high velocity penetrator (HVP) program. It is a powerful device capable of delivering a directed and very high pressure output that has been successfully employed to drive hypervelocity projectiles. The FST is configured from a hollow, high-explosive (HE) cylinder, a low-density Styrofoam core, and a one-point initiator at one end. A Mach stem is formed in the core as the forward-propagating, HE detonation wave intersects the reflected radial wave. This simple FST has been found to be a powerful pressure multiplier. Up to 1-Mbar output pressure can be obtained from this device. Further increase in the output pressure can be achieved by increasing the HE detonation velocity. The FST has been fine tuned to drive a thin plate to very high velocity under an impulse per unit area of about 1 Mbar[mu]s/cm[sup 2]. A 1.5-mm-thick stainless steel disk has been accelerated intact to 0.8 cm/[mu]s under a loading pressure rate of several Mbar/[mu]s. By making the plate curvature slightly convex at the loading side the authors have successfully accelerated it to almost 1.0 cm/[mu]s. The incorporation of a barrel at the end of the FST has been found to be important as confinement of the propellant gas by the barrel tends to accelerate the projectile to higher velocity. The desire to accelerate the plate above 1.0 cm/[mu]s provided the impetus to develop a more advanced fast shock tube to deliver a much higher output pressure. This report describes the investigation of a relatively simple air-lens phase-detonation system (PFST) with fifty percent higher phase-detonation velocity and a modest 2 Mbar output. Code calculations have shown that this PFST acceleration of a plate to about 1.2 cm/[mu]s can be achieved. The performance of these PFSTs has been evaluated and the details are discussed.

  5. Influence of and additives on acetylene detonation

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  6. Subnanosecond measurements of detonation fronts in solid high explosives

    NASA Astrophysics Data System (ADS)

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

    1984-04-01

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

  7. Numerical simulation of H2/air detonation using unstructured mesh

    NASA Astrophysics Data System (ADS)

    Togashi, Fumiya; Löhner, Rainald; Tsuboi, Nobuyuki

    2009-06-01

    To explore the capability of unstructured mesh to simulate detonation wave propagation phenomena, numerical simulation of H2/air detonation using unstructured mesh was conducted. The unstructured mesh has several adv- antages such as easy mesh adaptation and flexibility to the complicated configurations. To examine the resolution dependency of the unstructured mesh, several simulations varying the mesh size were conducted and compared with a computed result using a structured mesh. The results show that the unstructured mesh solution captures the detailed structure of detonation wave, as well as the structured mesh solution. To capture the detailed detonation cell structure, the unstructured mesh simulations required at least twice, ideally 5times the resolution of structured mesh solution.

  8. Multiple-cycle Simulation of a Pulse Detonation Engine Ejector

    NASA Technical Reports Server (NTRS)

    Yungster, S.; Perkins, H. D.

    2002-01-01

    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.

  9. The History of the Study of Detonation

    ERIC Educational Resources Information Center

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    In this article we reviewed the main concepts of detonative combustion. Concepts of slow and fast combustion, of detonation adiabat are introduced. Landmark works on experimental and semi-empirical detonation study are presented. We reviewed Chapman-Jouguet stationary detonation and spin detonation. Various mathematical model of detonation wave…

  10. Attenuation of a hydrogen-air detonation by acoustic absorbing covering

    NASA Astrophysics Data System (ADS)

    Bivol, G. Yu; Golovastov, S. V.; Golub, V. V.; Ivanov, K. V.; Korobov, A. E.

    2015-11-01

    Using of sound-absorbing surfaces to weaken and decay of a detonation wave in hydrogen-air mixtures was investigated experimentally. Experiments were carried out in a cylindrical detonation tube open at one end. Initiation of the explosive mixture was carried out by a spark discharge, which is located at the closed end of the detonation tube. Acoustical sound absorbing foam element of a specific weight of 0.035 g/cm3 with open pores of 0.5 mm was used. The degree of attenuation of the intensity of the detonation wave front was determined.

  11. Reverse slapper detonator

    SciTech Connect

    Weingart, Richard C.

    1990-01-01

    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.

  12. Detonation Reaction Zones in Condensed Explosives

    NASA Astrophysics Data System (ADS)

    Tarver, Craig

    2005-07-01

    Experimental measurements using nanosecond time resolved embedded gauges and laser interferometric techniques, combined with Non-Equilibrium Zeldovich -- von Neumann -- Doring (NEZND) theory and reactive flow hydrodynamic modeling, have revealed the average pressure/particle velocity states attained in reaction zones of self-sustaining detonation waves in several solid and liquid explosives. The time durations of these reaction zone processes is discussed for nitromethane, HMX, TATB and PETN. Progress in measuring and modeling the complex three-dimensional structural of these detonation waves is also 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.

  13. Synchro-ballistic recording of detonation phenomena

    SciTech Connect

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

    1997-09-01

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

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

    SciTech Connect

    Bdzil, J.B.; Jackson, T.L.; Stewart, D.S.

    1999-02-02

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

  15. Joining of tubes by gas detonation forming

    NASA Astrophysics Data System (ADS)

    Jenkouk, Vahid; Patil, Sandeep; Markert, Bernd

    2016-08-01

    For many applications, such as in structural components, it is required to join two tubes - sometimes with dissimilar material properties. Only few research studies have investigated the joining of tubular metallic components by means of high-velocity forming processes. In this paper, we present the novel process of joining of two tubes by a gas detonation pressure wave. In particular, the joining of a copper and a steel tube is discussed by means of a finite element study and a conducted experiment.

  16. Printable sensors for explosive detonation

    SciTech Connect

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

    2014-10-06

    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.

  17. Characterizing Detonator Output Using Dynamic Witness Plates

    NASA Astrophysics Data System (ADS)

    Murphy, Michael; Adrian, Ronald

    2009-06-01

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

  18. Heterodyne velocimetry and detonics experiments

    NASA Astrophysics Data System (ADS)

    Mercier, P.; Bénier, J.; Frugier, P. A.; Contencin, G.; Veaux, J.; Lauriot-Basseuil, S.; Debruyne, M.

    2008-11-01

    Heterodyne Velocimetry (or Photonic Doppler Velocimetry) has been used in detonics experiments for a few years now, mainly thanks to the recent evolution of telecom components. In its principle it is nothing else but a displacement interferometer, delivering beats versus time. A sliding Fourier transform processing on the raw signal thus allows to derive velocity versus time. The device is made up of a 1.55 μm Erbium laser delivering 2 W (split into 4 channels), single-mode optical fibers, fast photodetectors and digitizers (8 GHz bandwidth, 20 GS/s sampling). To begin with, we present a new heterodyne velocimeter setup embedding a second low-power frequency-tunable laser (50 mW) acting as a local oscillator. Its frequency can be shifted, to make it higher than the main laser, up to the bandwidth of the digitizer (13 GHz soon). The Doppler wave coming from the first laser and reflected by the moving target interferes with this shifted reference, therefore doubling the overall bandwidth of the system. On top of enhancing the measurable velocity range, the existence of beats at static gives a convenient means to tune the power levels of the laser and match the electric signal to the dynamics of the detector. Finally, three applications are presented: the first one deals with the classical measurement of free surface velocity on metallic shock loaded plates, in the second part we present the velocity distribution of tin particles ejected under shock. The third application relates to direct measurement of the velocity of detonation wave into nitromethane, by using immersed optical fibers.

  19. PIC-DSMC analysis on interaction of a laser induced discharge and shock wave

    NASA Astrophysics Data System (ADS)

    Shimamura, Kohei

    2015-09-01

    Laser induced discharge and the shock wave have attracted great interest for use in the electrical engineering. When the high intensity laser (10 GW >) is focused in the atmosphere, the breakdown occurs and the discharge wave propagates toward to the laser irradiation. The shock wave is generated around the discharge wave, which is called as the laser supported detonation wave. After breakdown occurred, the initial electron of the avalanche ionization is produced by the photoionization due to the plasma radiation. It is well recognized that the radiation of the laser plasma affects the propagation mechanism of the laser induced discharge wave after the initiation of the breakdown. However, it is difficult to observe the interaction between the plasma radiation and the electron avalanche in the ionization-wave front in experimentally except in the high intensity laser. In the numerical calculation of the laser-induced discharge, the fluid dynamics based on the Navier-Stokes equation have been widely used. However, it is difficult to investigate the avalanche ionization at the wave front using the fluid dynamics simulation. To investigate the interaction of the ionization-wave front and the shock wave, it is appropriate to utilize the PIC-DSMC method. The present study showed the propagation of the ionization front of the discharge wave and the shock wave using the particle simulation. This work was supported by Kato Foundation for Promotion of Science and Japan Power Academy.

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

    SciTech Connect

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

    2007-07-25

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

  1. Detonation propagation in narrow gaps with various configurations

    NASA Astrophysics Data System (ADS)

    Monwar, M.; Yamamoto, Y.; Ishii, K.; Tsuboi, T.

    2007-08-01

    In general all detonation waves have cellular structure formed by the trajectory of the triple points. This paper aims to investigate experimentally the propagation of detonation in narrow gaps for hydrogen-oxygen-argon mixtures in terms of various gap heights and gap widths. The gap of total length 1500 mm was constructed by three pair of stainless plates, each of them was 500 mm in length, which were inserted in a detonation tube. The gap heights were varied from 1.2 mm to 3.0 mm while the gap widths were varied from 10 mm to 40 mm. Various argon dilution rates were tested in the present experiments to change the size of cellular structure. Attempts have been made by means of reaction front velocity, shock front velocity, and smoked foil to record variations of cellular structure inside the gaps. A combination probe composed of a pressure and an ion probe detected the arrival of the shock and the reaction front individually at one measurement point. Experimental results show that the number of the triple points contained in detonation front decreases with decrease in the gap heights and gap widths, which lead to larger cellular structures. For mixtures with low detonability, cell size is affected by a certain gap width although conversely cell size is almost independent of gap width. From the present result it was found that detonation propagation inside the gaps is strongly governed by the gap height and effects of gap width is dependent on detonability of mixtures.

  2. Clamp for detonating fuze

    NASA Technical Reports Server (NTRS)

    Holderman, E. J.

    1968-01-01

    Quick acting clamp provides physical support for a closely confined detonating fuse in an application requiring removal and replacement at frequent intervals during test. It can be designed with a base of any required strength and configuration to permit the insertion of an object.

  3. Environmentally Benign Stab Detonators

    SciTech Connect

    Gash, A

    2005-12-21

    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

  4. Combustion and Magnetohydrodynamic Processes in Advanced Pulse Detonation Rocket Engines

    NASA Astrophysics Data System (ADS)

    Cole, Lord Kahil

    A number of promising alternative rocket propulsion concepts have been developed over the past two decades that take advantage of unsteady combustion waves in order to produce thrust. These concepts include the Pulse Detonation Rocket Engine (PDRE), in which repetitive ignition, propagation, and reflection of detonations and shocks can create a high pressure chamber from which gases may be exhausted in a controlled manner. The Pulse Detonation Rocket Induced Magnetohydrodynamic Ejector (PDRIME) is a modification of the basic PDRE concept, developed by Cambier (1998), which has the potential for performance improvements based on magnetohydrodynamic (MHD) thrust augmentation. The PDRIME has the advantage of both low combustion chamber seeding pressure, per the PDRE concept, and efficient energy distribution in the system, per the rocket-induced MHD ejector (RIME) concept of Cole, et al. (1995). In the initial part of this thesis, we explore flow and performance characteristics of different configurations of the PDRIME, assuming quasi-one-dimensional transient flow and global representations of the effects of MHD phenomena on the gas dynamics. By utilizing high-order accurate solvers, we thus are able to investigate the fundamental physical processes associated with the PDRIME and PDRE concepts and identify potentially promising operating regimes. In the second part of this investigation, the detailed coupling of detonations and electric and magnetic fields are explored. First, a one-dimensional spark-ignited detonation with complex reaction kinetics is fully evaluated and the mechanisms for the different instabilities are analyzed. It is found that complex kinetics in addition to sufficient spatial resolution are required to be able to quantify high frequency as well as low frequency detonation instability modes. Armed with this quantitative understanding, we then examine the interaction of a propagating detonation and the applied MHD, both in one-dimensional and two

  5. New detonation concepts for propulsion and power generation

    NASA Astrophysics Data System (ADS)

    Braun, Eric M.

    A series of related analytical and experimental studies are focused on utilizing detonations for emerging propulsion and power generation devices. An understanding of the physical and thermodynamic processes for this unsteady thermodynamic cycle has taken over 100 years to develop. An overview of the thermodynamic processes and development history is provided. Thermodynamic cycle analysis of detonation-based systems has often been studied using surrogate models. A real gas model is used for a thermal efficiency prediction of a detonation wave based on the work and heat specified by process path diagrams and a control volume analysis. A combined first and second law analysis aids in understanding performance trends for different initial conditions. A cycle analysis model for an airbreathing, rotating detonation wave engine (RDE) is presented. The engine consists of a steady inlet system with an isolator which delivers air into an annular combustor. A detonation wave continuously rotates around the combustor with side relief as the flow expands towards the nozzle. Air and fuel enter the combustor when the rarefaction wave pressure behind the detonation front drops to the inlet supply pressure. To create a stable RDE, the inlet pressure is matched in a convergence process with the average combustor pressure by increasing the annulus channel width with respect to the isolator channel. Performance of this engine is considered using several parametric studies. RDEs require a fuel injection system that can cycle beyond the limits of mechanical valves. Fuel injectors composed of an orifice connected to a small plenum cavity were mounted on a detonation tube. These fuel injectors, termed fluidic valves, utilize their geometry and a supply pressure to deliver fuel and contain no moving parts. Their behavior is characterized in order to determine their feasibility for integration with high-frequency RDEs. Parametric studies have been conducted with the type of fuel injected

  6. Non ideal detonation of emulsion explosives mixed with metal particles

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  7. Minimum tube diameters for steady propagation of gaseous detonations

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  8. Numerical investigations on reignition behavior of detonation diffraction

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Han, Wen-Hu; Bi, Yong; Ding, Jian-Xu

    2016-02-01

    In this paper, by adopting a fifth-order weighted essentially non-oscillatory (WENO) scheme with a third-order TVD Runge-Kutta time stepping method for two-dimensional reactive Euler equations, a parallel code is developed, and reignition behavior after a self-sustaining detonation from the tube into free space filled with H2/O2 mixtures is investigated. The numerical results show that the initial pressure has a great influence on the detonation cellular width, and that as the initial pressure increases, the cellular width gradually decreases and the cellular shape changes from irregular structure to regular structure, demonstrating the detonation instability to stability transition. When the initial pressure is larger than 1.2 atm, the detonation wave expands over the edge of the splitter plate, reignition can come into being because enough transverse waves collide with each other at the leading edge of the expanding front. When the initial pressure is 1.2 atm, hot spots appear on the front, and ignite the combustible gas near the hot spots after detonation diffraction. When the initial pressure is 1.0 atm, reignition fails. These findings hint that a critical initial pressure exists between 1.0-1.2 atm for direct reignition after detonation diffraction.

  9. Non-ideal detonation behaviour of PBX 9502

    NASA Astrophysics Data System (ADS)

    Schoch, Stefan; Nikiforakis, Nikos

    2009-06-01

    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.

  10. Three-dimensional cellular structure of detonations in suspensions of aluminium particles

    NASA Astrophysics Data System (ADS)

    Khasainov, B.; Virot, F.; Veyssière, B.

    2013-05-01

    Recently, we have used scarce available data on the detonation cell size in suspensions of aluminium particles in air and oxygen to adjust the kinetic parameters of our two-phase model of detonations in these mixtures. The calculated detonation cell width was derived by means of two-dimensional (2D) unsteady simulations using an assumption of cylindrical symmetry of the flow in the tube. However, in reality, the detonation cells are three-dimensional (3D). In this work, we have applied the same detonation model which is based on the continuous mechanics of two-phase flows, for 3D numerical simulations of cellular detonation structures in aluminium particle suspensions in oxygen. Reasonable agreement on the detonation cell width was obtained with the aforementioned 2D results. The range of tube diameters where detonations in { Al/O}_2 mixture at a given particle size and concentration would propagate in the spinning mode has been estimated (these results make a complement to our previous analysis of spinning detonations in Al/air mixtures). Coupling these results with the dependencies of detonation cell size on the mean particle diameter is of great interest for the understanding of fundamental mechanisms of detonation propagation in solid particle suspensions in gas and can help to better guide the experimental studies of detonations in aluminium suspensions. It is shown that the part of detonation wave energy used for transverse kinetic energy of both gas and particles is quite small, which explains why the propagation velocity of spinning and multi-headed detonations reasonably agrees with the ideal CJ values.

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    According to the theory of Byers Brown, in a steady state detonation the entropy production between the shock and sonic locus is a maximum in a self-sustaining wave. This has shown to hold true for all one-dimensional cases. Applied to 2D steady curved detonation waves in a slab or cylindrical stick of explosive, Byers Brown suggested a novel variational approach for maximising the global entropy generation within the detonation driving zone, hence providing the solution of the self-sustaining detonation wave problem. Preliminary application of such a variational technique, albeit with simplfying assumptions, demonstrate its potential to provide a rapid and accurate solution method for the problem. In this paper, recent progress in the development of the 2D variational technique and validation of the maximum entropy concept are reported. The predictions of the theory are compared with high-resolution numerical simulations and with the predictions of existing Detonation Shock Dynamics theory.

  12. Estimation of the detonation cell size in gases

    NASA Astrophysics Data System (ADS)

    Kuchinskii, V. V.; Onosov, I. I.

    2011-06-01

    A simple method to calculate the parameters of a shock wave in a space between the shock wave front and the Chapman-Jouguet plane is considered. Solving a velocity equation, one can calculate the pressure, density, and temperature of the gas, as well as determine the size of a detonation region in a one-dimensional approximation. The dependences of the detonation region size on input parameters are derived. From these dependences, one can estimate the run of the same curves in the real situation.

  13. Miniature plasma accelerating detonator and method of detonating insensitive materials

    DOEpatents

    Bickes, Jr., Robert W.; Kopczewski, Michael R.; Schwarz, Alfred C.

    1986-01-01

    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.

  14. Miniature plasma accelerating detonator and method of detonating insensitive materials

    DOEpatents

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

    1985-01-04

    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.

  15. Safeguarding against sympathetic detonations

    SciTech Connect

    Glenn, J.G. . Energetic Materials Branch); Gunger, M. )

    1994-02-01

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

  16. Chemical Equilibrium Detonation

    NASA Astrophysics Data System (ADS)

    Bastea, Sorin; Fried, Laurence E.

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

  17. Role of inlet reactant mixedness on the thermodynamic performance of a rotating detonation engine

    NASA Astrophysics Data System (ADS)

    Nordeen, C. A.; Schwer, D.; Schauer, F.; Hoke, J.; Barber, T.; Cetegen, B. M.

    2016-07-01

    Rotating detonation engines have the potential to achieve the high propulsive efficiencies of detonation cycles in a simple and effective annular geometry. A two-dimensional Euler simulation is modified to include mixing factors to simulate the imperfect mixing of injected reactant streams. Contrary to expectations, mixing is shown to have a minimal impact on performance. Oblique detonation waves are shown to increase local stream thermal efficiency, which compensates for other losses in the flow stream. The degree of reactant mixing is, however, a factor in controlling the stability and existence of rotating detonations.

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

    SciTech Connect

    Murphy, Michael J; Clarke, Steven A; Munger, Alan C; Thomas, Keith A

    2009-01-01

    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.

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

    SciTech Connect

    Francois, Elizabeth Green; Morris, John S; Novak, Alan M; Kennedy, James E

    2010-01-01

    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.

  20. Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

    NASA Astrophysics Data System (ADS)

    Zhang, Xu-Dong; Fan, Bao-Chun; Gui, Ming-Yue; Pan, Zhen-Hua; Dong, Gang

    2012-02-01

    Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonationshock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interesting properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

  1. Parameters, limits, attenuation, and suppression of detonation in mixtures of an explosive gas with chemically inert microparticles

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Fomin, P. A.; Tropin, D. A.; Chen, Z.-R.

    2012-03-01

    Chapman-Jouguet parameters and the cell size of a detonation wave in mixtures of an explosive gas with chemically inert particles have been calculated. The algorithm of calculation of the minimum mass and characteristic dimension of a particle cloud ensuring successful suppression of detonation in the gas has been proposed. The calculation results are in good agreement with the available experimental data. The influence of the initial composition of the gas on the efficiency of suppression of the detonation wave has been analyzed. The issue of the dependence of the concentration limits of detonation on the mass fraction of particles has been investigated. It has been established that the increase in the concentration of the condensed phase leads to a narrowing of the existence domain of detonation and that the propagation of the detonation wave becomes impossible when the concentration of the particles is fairly high.

  2. Recent work on gaseous detonations

    NASA Astrophysics Data System (ADS)

    Nettleton, M. A.

    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.

  3. Experimental Study on DDT Characteristics in Spiral Configuration Pulse Detonation Engines

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

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

  5. Low voltage nonprimary explosive detonator

    DOEpatents

    Dinegar, Robert H.; Kirkham, John

    1982-01-01

    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.

  6. Laser supported solid state absorption fronts in silica

    SciTech Connect

    Carr, C W; Bude, J D

    2010-02-09

    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.

  7. Laser-supported solid-state absorption fronts in silica

    NASA Astrophysics Data System (ADS)

    Carr, C. W.; Bude, J. D.; Demange, P.

    2010-11-01

    We develop a model based on simulation and extensive experimentation that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm2 ) laser exposure. Both experiments and simulations show that the absorption front velocity is constant in time and is nearly linear in laser intensity. Further, this model can explain the dependence of laser damage site size on these parameters. We show that these absorption fronts naturally result from the combination of high-temperature-activated deep subband-gap optical absorptivity, free-electron transport, and thermal diffusion in defect-free silica for temperatures up to 15000K and pressures <10GPa . The regime of parameter space critical to this problem spans and extends that measured by other means. It serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

  8. Initiation of detonation regimes in hybrid two-phase mixtures

    NASA Astrophysics Data System (ADS)

    Khasainov, B. A.; Veyssiere, B.

    1996-06-01

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

  9. Acceleration of solid particles by gaseous detonation products

    SciTech Connect

    Gavrilenko, T.P.; Grigoriev, V.V.; Zhdan, S.A.; Nikolaev, Y.A.; Boiko, V.M.; Papyrin, A.N.

    1986-11-01

    This investigation is concerned with a theoretical and experimental study of acceleration dynamics of spherically inert solid particles (100 ..mu..m nominal diameter) in flows of gaseous detonation products. The experiments were conducted in a detonation channel 1.5 m long with a 20 x 20 mm/sup 2/ cross section and one open end. Particle motion was observed with the method of multiexposure photographic recording and a laser stroboscopic light source. The character of velocity variation of individual particles inside and outside of the channel was investigated for different initial positions of particles. Under certain conditions the accelerated particles are destroyed. A mathematical model based on two-phase multivelocity continuum mechanics has been formulated to describe the detonation wave propagation, outflow of detonation products from the channel, and interaction between particles and a nonstationary flow of detonation products. The model includes chemical equilibrium of detonation products, particle acceleration, heat exchange between phases and channel walls, particle melting, and fragmentation of droplets if the Weber number exceeds some critical value. Particle destruction has been correlated with the initial position, diameter, and physical properties of particles. Comparison of computer and experimental results shows that the model satisfactorily describes acceleration, heating, and fragmentation of particles.

  10. Detonation performance of high-dense BTF charges

    NASA Astrophysics Data System (ADS)

    Dolgoborodov, Alexander; Brazhnikov, Michael; Makhov, Michael; Gubin, Sergey; Maklasova, Irina

    2013-06-01

    New experimental data on detonation wave parameters and explosive performance for benzotrifuroxan (BTF) are presented. Optical pyrometry was applied in order to measure the temperature and pressure of BTF detonation products. Chapman-Jouguet pressure and temperature were obtained as following: 33.8 GPa and 3990 K; 34.5 GPa and 4170 K (initial charge densities 1.82 and 1.84 g/cc respectively), the polytropic exponent was estimated as 2.8. The heat of explosion and acceleration ability were measured also. The results of calorimetric measurements performed in bomb calorimeter indicate that BTF slightly surpasses HMX in the heat of explosion. However BTF is inferior to HMX in the acceleration ability, measured by the method of copper casing expansion. It is also considered the hypothesis of formation of nanocarbon particles in detonation products directly behind the detonation front and influence of this processes on the temperature-time history in detonation products. The results of calculations with in view of formation of liquid nanocarbon in products of a detonation also are presented.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  12. Design and optimization of a deflagration to detonation transition (ddt) section

    NASA Astrophysics Data System (ADS)

    Romo, Francisco X.

    Throughout the previous century, hydrocarbon-fueled engines have used and optimized the `traditional' combustion process called deflagration (subsonic combustion). An alternative form of combustion, detonation (supersonic combustion), can increase the thermal efficiency of the process by anywhere from 20 - 50%. Even though several authors have studied detonation waves since the 1890's and a plethora of papers and books have been published, it was not until 2008 that the first detonation-powered flight took place. It lasted for 10 seconds at 100 ft. altitude. Achieving detonation presents its own challenges: some fuels are not prone to detonate, severe vibrations caused by the cyclic nature of the engine and its intense noise are some of the key areas that need further research. Also, to directly achieve detonation either a high-energy, bulky, ignition system is required, or the combustion chamber must be fairly long (5 ft. or more in some cases). In the latter method, a subsonic flame front accelerates within the combustion chamber until it reaches supersonic speeds, thus detonation is attained. This is called deflagration-todetonation transition (DDT). Previous papers and experiments have shown that obstacles, such as discs with an orifice, located inside the combustion chamber can shorten the distance required to achieve detonation. This paper describes a hands-on implementation of a DDT device. Different disc geometries inside the chamber alter the wave characteristics at the exit of the tube. Although detonation was reached only when using pure oxygen, testing identified an obstacle configuration for LPG and air mixtures that increased pressure and wave speed significantly when compared to baseline or other obstacle configurations. Mixtures of LPG and air were accelerated to Mach 0.96 in the downstream frame of reference, which would indicate a transition to detonation was close. Reasons for not achieving detonation may include poor fuel and oxidizer mixing

  13. Modeling Detonation of Heterogeneous Explosives with Embedded Inert Particles Using Detonation Shock Dynamics: Normal and Divergent Propagation in Regular and Simplified Microstructure

    NASA Astrophysics Data System (ADS)

    Stewart, Scott

    2012-11-01

    We use a detonation shock propagation model, Detonation Shock Dynamics (DSD) to compute the interaction of a detonation shock wave that passes over a series of inert spherical particles embedded in a high explosive material. DSD provides an efficient means to study the dynamics of lead shock waves without the necessity of simulating the entire multi-material, reactive flow field. We derive partial differential equations for the motion of a detonation shock that obeys a linear shock normal velocity-curvature relation in a cylindrical coordinate system and in a moving, shock-attached coordinate system. The shock dynamics equations are solved numerically, in a unit-cell configuration. We describe the short-term and long-term behavior of the shock wave as it passes over the particles. We describe both the averages and character of the stochastic behavior that affects long-term average properties for microstructure in which the inert particles are periodically and randomly spaced.

  14. 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)

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

    2014-07-01

    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.

  15. Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.

    2001-01-01

    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

  16. Integrated Pulse Detonation Propulsion and Magnetohydrodynamic Power

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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

  17. Effect of slow energy releasing on divergent detonation of Insensitive High Explosives

    NASA Astrophysics Data System (ADS)

    Hu, Xiaomian; Pan, Hao; Huang, Yong; Wu, Zihui

    2014-03-01

    There exists a slow energy releasing (SER) process in the slow reaction zone located behind the detonation wave due to the carbon cluster in the detonation products of Insensitive High Explosives (IHEs), and the process will affect the divergent detonation wave's propagation and the driving process of the explosives. To study the potential effect, a new artificial burn model including the SER process based on the programmed burn model is proposed in the paper. Quasi-steady analysis of the new model indicates that the nonlinearity of the detonation speed as a function of front curvature owes to the significant change of the reaction rate and the reaction zone length at the sonic state. What's more, in simulating the detonation of IHE JB-9014, the new model including the slow reaction can predict a slower jump-off velocity, in good agreement with the result of the test.

  18. Characterizing detonator output using dynamic witness plates

    SciTech Connect

    Murphy, Michael John; Adrian, Ronald J

    2009-01-01

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

  19. Smooth blasting with the electronic delay detonator

    SciTech Connect

    Yamamoto, Masaaki; Ichijo, Toshiyuki; Tanaka, Yoshiharu

    1995-12-31

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

  20. Characterizing Detonator Output Using Dynamic Witness Plates

    NASA Astrophysics Data System (ADS)

    Murphy, Michael J.; Adrian, Ronald J.

    2009-12-01

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

  1. Reaction zone measurements in detonating aluminized explosives

    NASA Astrophysics Data System (ADS)

    Lubyatinsky, S. N.; Loboiko, B. G.

    1996-05-01

    Detonation reaction zone measurements have been made on five RDX-based explosives (60 μm average particle size RDX), containing 6% polymer binder and from 0 to 19% aluminum of different particle size (from 2 μm to 20 μm). A photoelectric technique was employed to record the radiation intensity history of the shock front propagating through chloroform in contact with the charge face. The record was then translated into the explosive/chloroform interface velocity history. In all cases, the Zeldovich-von Neumann-Doering detonation wave structure was observed. Aluminum particle size was found to have no appreciable effect on the reaction zone length, which increases from 0.34 mm to 0.58 mm as aluminum content increases from 0 to 19%. Nevertheless, the reaction zone lengths of the studied explosives are less than that of RDX/TNT 50/50 (0.59 mm), which implies relatively high rate of the reaction between aluminum and RDX detonation products.

  2. Detonation Failure Characterization of Non-Ideal Explosives

    NASA Astrophysics Data System (ADS)

    Janesheski, Robert; Son, Steven; Groven, Lori

    2011-06-01

    Non-ideal explosives are currently poorly characterized, which limits the modeling of them. Current characterization requires large-scale testing to obtain detonation wave characterization for analysis due to the relatively thick reaction zones. Use of a microwave interferometer applied to small-scale confined experiments is being implemented to allow for time resolved characterization of a failing detonation. The microwave interferometer measures the failing detonation wave in a tube, and this experiment only requires small amounts of non-ideal explosives. A non-ideal explosive is initiated with a booster charge and a measurement of the failure distance and a continuous position-time trace of the detonation front location can be obtained. Initial tests have been performed that show this method is feasible using an ammonium perchlorate (AP) composite propellant as a model non-ideal explosive. Future work will apply this approach to non-ideal explosives. Successful results of this method would allow for the calibration of detonation models for many different non-ideal explosives. This project was funded by the Department of Homeland Security through the Center of Excellence for Explosive Detection, Mitigation, and Response under award number 080409/0002251.

  3. Non ideal detonation of emulsion explosives mixed with metal particles

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    The detonation of ammonium nitrate based compositions like emulsion explosives mixed with metal particles was experimentally investigated. Aluminum powder with a mean particle size of 6 μm was used, and the mass concentration of aluminum on the explosive charge ranged from 0 to 30% wt. The values of the detonation velocity, the pressure attenuation - P(x) - of the shock front amplitude in a standard PMMA monitor and manganin gauges pressure-time histories are shown as a function of the explosive charge porosity and specific mass. All these parameters except the pressuretimes histories have been evaluated using the multi-fiber optical probe (MFOP) method which is based on the use of an optical fiber strip, with 64 independent optical fibers. The MFOP allows a quasicontinuous evaluation of the detonation wave run propagation and the assessment of spatial resolved measurements of the shock wave induced in the PMMA barrier. Results of that characterization process are presented and discussed for aluminized and non-aluminized emulsion explosives. The experimental results have shown that the detonation velocity decreases monotonically with the increase of aluminum content. Nevertheless the peak of detonation pressure profiles presents a non-monotonic behavior increasing its value up to an Al content of 20% wt, after which it starts to decrease.

  4. Semiconductor bridge (SCB) detonator

    DOEpatents

    Bickes, Jr., Robert W.; Grubelich, Mark C.

    1999-01-01

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge 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.

  5. Semiconductor bridge (SCB) detonator

    DOEpatents

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

    1999-01-19

    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.

  6. Pulse Detonation Engine Modeled

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.

    2001-01-01

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

  7. Deflagration-to-Detonation Transition of Methane-Oxygen Mixtures in Narrow Tubes

    NASA Astrophysics Data System (ADS)

    Golub, V. V.; Golovastov, S. V.; Ivanov, K. V.; Baklanov, D. I.; Lenkevich, D. A.; Kotelnikov, A. L.

    For recent technical applications it is necessary to reduce the distance between the point of ignition and the actual point of the detonation wave. It is basically related to the requirements of portability of an application.

  8. Detonator-activated ball shutter

    DOEpatents

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

    1983-08-16

    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.

  9. Detonator-activated ball shutter

    DOEpatents

    McWilliams, Roy A.; von Holle, William G.

    1983-01-01

    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.

  10. Pulse Detonation Rocket Magnetohydrodynamic Power Experiment

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  11. Behavior of detonation propagation in mixtures with concentration gradients

    NASA Astrophysics Data System (ADS)

    Ishii, K.; Kojima, M.

    2007-08-01

    Behavior of detonation waves in mixtures with concentration gradients normal to the propagation direction was studied experimentally. Mixtures with various concentration gradients were formed by sliding the separation plate which divides a detonation chamber from a diffusion chamber in which a diffusion gas was initially introduced. A stoichiometric hydrogen-oxygen mixture was charged in the detonation chamber, while oxygen or nitrogen was filled in the diffusion gas chamber. Temporal concentration measurement was conducted by the infrared absorption method using ethane as alternate of oxygen. Smoked foil records show a deformation of regular diamond cells to parallelogram ones, which well corresponds to local mixture concentration. Schlieren photographs reveal the tilted wave front whose angle is consistent with the deflection angle of the detonation front obtained from trajectories of the triple point. The local deflection angle increases with increase in local concentration gradient. Calculation of wave trajectory based on the ray tracing theory predicts formation of the tilted wave front from an initial planar front.

  12. Detonation Reaction Zones in Condensed Explosives

    NASA Astrophysics Data System (ADS)

    Tarver, Craig M.

    2006-07-01

    Experimental measurements using nanosecond time resolved embedded gauges and laser interferometric techniques, combined with Non-Equilibrium Zeldovich - von Neumann - Doling (NEZND) theory and Ignition and Growth reactive flow hydrodynamic modeling, have revealed the average pressure/particle velocity states attained in reaction zones of self-sustaining detonation waves in several solid and liquid explosives. The time durations of these reaction zone processes are discussed for explosives based on pentaerythritol tetranitrate (PETN), nitromethane, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), triaminitrinitrobenzene(TATB) and trinitrotoluene (TNT).

  13. Detonation Reaction Zones in Condensed Explosives

    SciTech Connect

    Tarver, C M

    2005-07-14

    Experimental measurements using nanosecond time resolved embedded gauges and laser interferometric techniques, combined with Non-Equilibrium Zeldovich--von Neumann--Doring (NEZND) theory and Ignition and Growth reactive flow hydrodynamic modeling, have revealed the average pressure/particle velocity states attained in reaction zones of self-sustaining detonation waves in several solid and liquid explosives. The time durations of these reaction zone processes is discussed for explosives based on pentaerythritol tetranitrate (PETN), nitromethane, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), triaminitrinitrobenzene(TATB) and trinitrotoluene (TNT).

  14. The dynamics of unsteady detonation in ozone

    SciTech Connect

    Aslam, Tariq D; Powers, Joseph M

    2008-01-01

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

  15. Diamonds in detonation soot

    NASA Technical Reports Server (NTRS)

    Greiner, N. Roy; Phillips, Dave; Johnson, J. D.; Volk, Fred

    1990-01-01

    Diamonds 4 to 7 nm in diameter have been identified and partially isolated from soot formed in detonations of carbon-forming composite explosives. The morphology of the soot has been examined by transmission electron microscopy (TEM), and the identity of the diamond has been established by the electron diffraction pattern of the TEM samples and by the X-ray diffraction (XRD) pattern of the isolated solid. Graphite is also present in the form of ribbons of turbostatic structure with a thickness of 2 to 4 nm. A fraction, about 25 percent of the soot by weight, was recovered from the crude soot after oxidation of the graphite with fuming perchloric acid. This fraction showed a distinct XRD pattern of diamond and the diffuse band of amorphous carbon. The IR spectrum of these diamonds closely matches that of diamonds recovered from meteorites (Lewis et al., 1987), perhaps indicating similar surface properties after the oxidation. If these diamonds are produced in the detonation itself or during the initial expansion, they exhibit a phenomenal crystal growth rate (5 nm/0.00001 s equal 1.8 m/hr) in a medium with a very low hydrogen/carbon ratio. Because the diamonds will be carried along with the expanding gases, they will be accelerated to velocities approaching 8 km/s.

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

    SciTech Connect

    Short, Mark; Kiyanda, Charles B; Quirk, James J; Sharpe, Gary J

    2011-01-27

    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

  17. The influence of structural response on sympathetic detonation

    NASA Technical Reports Server (NTRS)

    Watson, J. L.

    1980-01-01

    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.

  18. Vortex formation in a proposed detonation internal combustion engine

    SciTech Connect

    Loth, E.

    1995-05-01

    A possible configuration for taking advantage of detonation combustion in an internal combustion engine is described, which uses a separate detonation combustion chamber that discharges tangentially into a vortex chamber formed by the piston and cylinder at top dead center. The vortex chamber is designed to efficiently store a portion of the kinetic energy produced by the detonation wave in the form of a vortex, which would subsequently be converted into static pressure. By placing this chamber above the piston surface, the detonation and primary shock waves are directed parallel to the piston surface, thus avoiding potentially destructive loads to the piston. The rapid burning followed by mixing with air in the vortex chamber may reduce the formation of NOx and unburned hydrocarbons as compared to conventional combustion. Such a configuration may efficiently take advantage of clean-burning slow-deflagrating fuels such as natural gas to yield constant volume-type efficiencies. Shock wave propagation through the vortex chamber was simulated to qualitatively observe the vortex storage and rapid mixing characteristics. 30 refs.

  19. A thermochemically derived global reaction mechanism for detonation application

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Yang, J.; Sun, M.

    2012-07-01

    A 4-species 4-step global reaction mechanism for detonation calculations is derived from detailed chemistry through thermochemical approach. Reaction species involved in the mechanism and their corresponding molecular weight and enthalpy data are derived from the real equilibrium properties. By substituting these global species into the results of constant volume explosion and examining the evolution process of these global species under varied conditions, reaction paths and corresponding rates are summarized and formulated. The proposed mechanism is first validated to the original chemistry through calculations of the CJ detonation wave, adiabatic constant volume explosion, and the steady reaction structure after a strong shock wave. Good agreement in both reaction scales and averaged thermodynamic properties has been achieved. Two sets of reaction rates based on different detailed chemistry are then examined and applied for numerical simulations of two-dimensional cellular detonations. Preliminary results and a brief comparison between the two mechanisms are presented. The proposed global mechanism is found to be economic in computation and also competent in description of the overall characteristics of detonation wave. Though only stoichiometric acetylene-oxygen mixture is investigated in this study, the method to derive such a global reaction mechanism possesses a certain generality for premixed reactions of most lean hydrocarbon mixtures.

  20. Detonation spreading in fine TATBs

    SciTech Connect

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

    1998-12-31

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

  1. New generation detonics

    SciTech Connect

    Souers, P.C.

    1996-12-15

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

  2. Preparation of C60 by Detonation Technique

    NASA Astrophysics Data System (ADS)

    Wei, Xianfeng; Han, Yong; Long, Xinping

    2012-11-01

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

  3. Mathematical modeling of detonation initiation via flow cumulation effects

    NASA Astrophysics Data System (ADS)

    Semenov, I.; Utkin, P.; Akhmedyanov, I.

    2016-07-01

    The paper concerns two problems connected with the idea of gaseous detonation initiation via flow cumulation effects and convergence of relatively weak shock waves (SW). The first one is the three-dimensional (3D) numerical investigation of shock-to-detonation transition (SDT) in methane-air mixture in a tube with parabolic contraction followed by the tube section of narrow diameter and conical expansion. The second problem is the numerical study of the start-up of the model small-scale hydrogen electrochemical pulse detonation engine with the use of electrical discharge generating the toroidal SW. The investigation is performed by means of numerical simulation with the use of modern high-performance computing systems.

  4. [The Diagnostics of Detonation Flow External Field Based on Multispectral Absorption Spectroscopy Technology].

    PubMed

    Lü, Xiao-jing; Li, Ning; Weng, Chun-sheng

    2016-03-01

    show that both of the temperature and H2O concentration rose with the arrival of detonation wave. With the increase of the vertical distance between the detonation tube nozzle and the laser path, the time of temperature and concentration coming to the peak delayed, and the temperature variation trend tended to slow down. At 20 cm from detonation tube nozzle, the maximum temperature hit 1 329 K and the maximum H2O concentration of 0.19 occurred at 4 ms after ignition. The research can provide with us the support for expanding the detonation test field with absorption spectroscopy technology, and can also help to promote the detonation mechanism research and to enhance the level of detonation engine control technology. PMID:27400494

  5. [The Diagnostics of Detonation Flow External Field Based on Multispectral Absorption Spectroscopy Technology].

    PubMed

    Lü, Xiao-jing; Li, Ning; Weng, Chun-sheng

    2016-03-01

    show that both of the temperature and H2O concentration rose with the arrival of detonation wave. With the increase of the vertical distance between the detonation tube nozzle and the laser path, the time of temperature and concentration coming to the peak delayed, and the temperature variation trend tended to slow down. At 20 cm from detonation tube nozzle, the maximum temperature hit 1 329 K and the maximum H2O concentration of 0.19 occurred at 4 ms after ignition. The research can provide with us the support for expanding the detonation test field with absorption spectroscopy technology, and can also help to promote the detonation mechanism research and to enhance the level of detonation engine control technology.

  6. The development and testing of pulsed detonation engine ground demonstrators

    NASA Astrophysics Data System (ADS)

    Panicker, Philip Koshy

    2008-10-01

    The successful implementation of a PDE running on fuel and air mixtures will require fast-acting fuel-air injection and mixing techniques, detonation initiation techniques such as DDT enhancing devices or a pre-detonator, an effective ignition system that can sustain repeated firing at high rates and a fast and capable, closed-loop control system. The control system requires high-speed transducers for real-time monitoring of the PDE and the detection of the detonation wave speed. It is widely accepted that the detonation properties predicted by C-J detonation relations are fairly accurate in comparison to experimental values. The post-detonation flow properties can also be expressed as a function of wave speed or Mach number. Therefore, the PDE control system can use C-J relations to predict the post-detonation flow properties based on measured initial conditions and compare the values with those obtained from using the wave speed. The controller can then vary the initial conditions within the combustor for the subsequent cycle, by modulating the frequency and duty cycle of the valves, to obtain optimum air and fuel flow rates, as well as modulate the energy and timing of the ignition to achieve the required detonation properties. Five different PDE ground demonstrators were designed, built and tested to study a number of the required sub-systems. This work presents a review of all the systems that were tested, along with suggestions for their improvement. The PDE setups, ranged from a compact PDE with a 19 mm (3/4 in.) i.d., to two 25 mm (1 in.) i.d. setups, to a 101 mm (4 in.) i.d. dual-stage PDE setup with a pre-detonator. Propane-oxygen mixtures were used in the smaller PDEs. In the dual-stage PDE, propane-oxygen was used in the pre-detonator, while propane-air mixtures were used in the main combustor. Both rotary valves and solenoid valve injectors were studied. The rotary valves setups were tested at 10 Hz, while the solenoid valves were tested at up to 30 Hz

  7. Modeling Detonation in Ultrafine TATB Hemispherical Boosters Using CREST

    NASA Astrophysics Data System (ADS)

    Whitworth, Nicholas

    2011-06-01

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

  8. Modelling detonation in ultrafine tatb hemispherical boosters using crest

    NASA Astrophysics Data System (ADS)

    Whitworth, Nicholas J.

    2012-03-01

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

  9. Development of an Actuator for Flow Control Utilizing Detonation

    NASA Technical Reports Server (NTRS)

    Lonneman, Patrick J.; Cutler, Andrew D.

    2004-01-01

    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.

  10. Detonation tube impulse in sub-atmospheric environments.

    SciTech Connect

    Cooper, Marcia A.; Shepherd, Joseph E.

    2005-04-01

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

  11. Detonation propagation in hydrogen-air mixtures with transverse concentration gradients

    NASA Astrophysics Data System (ADS)

    Boeck, L. R.; Berger, F. M.; Hasslberger, J.; Sattelmayer, T.

    2016-03-01

    The influence of transverse concentration gradients on detonation propagation in H_2-air mixtures is investigated experimentally in a wide parameter range. Detonation fronts are characterized by means of high-speed shadowgraphy, OH* imaging, pressure measurements, and soot foils. Steep concentration gradients at low average H_2 concentrations lead to single-headed detonations. A maximum velocity deficit compared to the Chapman-Jouguet velocity of 9 % is observed. Significant amounts of mixture seem to be consumed by turbulent deflagration behind the leading detonation. Wall pressure measurements show high local pressure peaks due to strong transverse waves caused by the concentration gradients. Higher average H_2 concentrations or weaker gradients allow for multi-headed detonation propagation.

  12. Detonation Propagation through Nitromethane Embedded Metal Foam

    NASA Astrophysics Data System (ADS)

    Lieberthal, Brandon; Maines, Warren R.; Stewart, D. Scott

    2015-11-01

    There is considerable interest in developing a better understanding of dynamic behaviors of multicomponent systems. We report results of Eulerian hydrodynamic simulations of shock waves propagating through metal foam at approximately 20% relative density and various porosities using a reactive flow model in the ALE3D software package. We investigate the applied pressure and energy of the shock wave and its effects on the fluid and the inert material interface. By varying pore sizes, as well as metal impedance, we predict the overall effects of heterogeneous material systems at the mesoscale. In addition, we observe a radially expanding blast front in these heterogeneous models and apply the theory of Detonation Shock Dynamics to the convergence behavior of the lead shock.

  13. Gaseous hydrocarbon-air detonations

    SciTech Connect

    Tieszen, S.R.; Stamps, D.W.; Westbrook, C.K.; Pitz, W.J.

    1988-01-01

    Detonation cell width measurements are made on mixtures of air and methane, ethane, dimethyl-ether, nitroethane, ethylene, acetylene, propane, 1,2-epoxypropane, n-hexane, 1-nitrohexane, mixed primary hexylnitrate, n-octane, 2,2,4-trimethylpentane, cyclooctane, 1-octene, cis-cyclooctene, 1-7-octadiene, 1-octyne, n-decane, 1,2-epoxydecane, pentyl-ether, and JP4. There is a slight decrease in detonation cell width that is within the uncertainty of the data for stoichiometric alkanes, alkenes, and alkynes with increasing temperature between 25 and 100/degree/C. Also there appears to be no effect of molecular weight from ethane to decane, on detonation cell width for stoichiometric alkanes. Molecular structure is found to affect detonability for C/sub 8/ hydrocarbons, where the saturated ring structure is more sensitive than the straight-chain alkane. Unsaturated alkenes and alkynes are more sensitive to detonation than saturated alkanes. However, the degree of sensitization decreases with increasing molecular weight. Addition of functional groups such as nitro, nitrate, epoxy, and ethers are found to significantly reduce the detonation cell width from the parent n-alkane. Nitrated n-alkanes can be more sensitive than hydrogen-air mixtures. The increase in sensitivity of epoxy groups appears to be related to the oxygen to carbon ratio of the molecule. Good results are obtained between the data and predictions from a ZND model with detailed chemical kinetics. 46 refs., 8 figs., 4 tabs.

  14. The Physics of White Dwarf Mergers and Detonations: A Path to Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Chang, Philip

    This project will investigate the double degenerate scenario for Type Ia supernova (SN Ia) and the physics of detonation initiation in white dwarfs. While the progenitors of SN Ia are not known, the detonation of a remnant from a pair of merging white dwarfs produces a mix of burnt material that is similar to the compositional makeup of SN Ia. Hence, the merger of two white dwarfs and detonation of its relaxed remnant is a promising avenue to SN Ia. Using a combination of numerical and analytic techniques, the PI and his collaborators will investigate the merger of two white dwarfs and the initiation of detonations in these remnants. In particular, the group will use a previously modified smooth particle hydrodynamics code to perform a parameter study of the mergers of two white dwarfs. The group will then determine how the properties of the resulting remnant depends on it initial conditions of the merger. In doing so, the group will map out the parameter space of white dwarf mergers, whose remnant's secular evolution that can lead to Type Ia supernova. The group will also investigate the physics of detonation initiation in WDs. In particular, the group will leverage prior work on terrestial detonations to map the controlling parameters of detonation initiation in WDs. For instance, the group will determine the physics of detonations for a given size and shape of a hotspot, i.e., if the detonation occurs due pure combustion effects or if the interaction between combustion waves and hydrodynamics waves are important. Armed with this information, the group will proceed to study if large scale turbulence can give rise the hotspots capable of initiating detonations and the physics of these initiations. The work performed by this group will be important in future dark energy survey mission such as a WFIRST descendent and in current transient all-sky surveys.

  15. Theoretical analysis of rotating two phase detonation in a rocket motor

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    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.

  16. Features of the dynamics of postdetonation waves

    NASA Astrophysics Data System (ADS)

    Gimaltdinov, I. K.; Arslanbekova, R. R.; Levina, T. M.

    2016-05-01

    We present the results of numerical investigations of the parameters of postdetonation waves forming at a passage from the zone occupied with a bubbly liquid formed by the detonation wave to a zone filled with a liquid without bubbles. The dependence of the pressure amplitude of detonation waves and postdetonation waves on the gas volumetric content of bubbles has been studied. A possibility of the detonation transfer through the layer of a bubble-free liquid separating the regions of the bubbly liquid has been shown, the map of possible situations at the detonation transfer through the layer of this liquid has been presented.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  18. Optimization of detonation velocity measurements using a chirped fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Barbarin, Y.; Lefrançois, A.; Zaniolo, G.; Chuzeville, V.; Jacquet, L.; Magne, S.; Luc, J.; Osmont, A.

    2015-05-01

    Dynamic measurements of detonation velocity profiles are performed using long Chirped Fiber Bragg Gratings (CFBGs). Such thin probes, with a diameter of typically 150 μm, are inserted directly into a high explosive sample or simply positioned laterally. During the detonation, the width of the reflected optical spectrum is continuously reduced by the propagation of the wave-front, which physically shortens the CFBG. The reflected optical intensity delivers a ramp down signal type, which is directly related to the detonation velocity profile. Experimental detonation velocity measurements were performed on the side of three different high explosives (TNT, B2238 and V401) in a bare cylindrical stick configuration (diameter: 2 inches, height: 10 inches). The detonation velocity range covered was 6800 to 9000 m/s. The extraction of the detonation velocity profiles requires a careful calibration of the system and of the CFBG used. A calibration procedure was developed, with the support of optical simulations, to cancel out the optical spectrum distortions from the different optical components and to determine the wavelength-position transfer function of the CFBG in a reproducible way. The 40-mm long CFBGs were positioned within the second half of the three high explosive cylinders. The excellent linearity of the computed position-time diagram confirms that the detonation was established for the three high explosives. The fitted slopes of the position-time diagram give detonation velocity values which are in very good agreement with the classical measurements obtained from discrete electrical shorting pins.

  19. Characterization of shock and reaction fronts in detonations

    NASA Astrophysics Data System (ADS)

    Tulis, Allen J.; Selman, J. Robert

    1982-10-01

    An instrumental technique has been developed which allows the concomitant measurement of the arrival times of both shock and reaction (flame) fronts in propagating detonations. A combination of fiber-optic probes and light detectors is used to monitor the arrival of the reaction front, whereas piezoelectric pressure gauges monitor the arrival of the pressure pulse from the preceding shock wave. Both signals provide the measurement of the detonation velocity; variance between shock and reaction front velocities implies nonstable detonation (growing or dying detonation) which can be attributed to variation in density, concentration, or homogeneity of the detonating media. This technique is straightforward in the case of pressed or cast formulations but presents difficulties when gas-phase or two-phase detonations are involved. The detonation of near-stoichiometric ethylene-air mixtures in a detonation-tube facility was used to refine the technique and calibrate the instrumentation. The technique was then used to characterize the detonation of two-phase aluminum powder-air mixtures of various concentrations. Compared to the 3-μs induction time between the shock and reaction fronts in the case of ethylene-air mixtures, the induction times for aluminum powder-air mixtures varied from about 1 to over 100 μs. The variation in induction time was attributed to several factors: extended heating time to ignition of the particles due to inhomogeneity of the two-phase mixtures; variation in particle size; and variable aluminum-oxide surface coating thickness. The concentration of aluminum powder in the air was monitored dynamically using instrumentation that related the concentration of aluminum to the attenuation of a laser beam through the mixture. A mean, or overall, value was also estimated by determining the mass flow rate and overall discharge time using photographic coverage. In the former case, in order to obtain meaningful signals for these high-concentration two

  20. Detonation propagation and Mach stem formation in PBXN-9

    SciTech Connect

    Hull, L.M.

    1997-09-01

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

  1. Towards Integrated Pulse Detonation Propulsion and MHD Power

    NASA Technical Reports Server (NTRS)

    Litchford, Ron J.; Thompson, Bryan R.; Lineberry, John T.

    1999-01-01

    The interest in pulse detonation engines (PDE) arises primarily from the advantages that accrue from the significant combustion pressure rise that is developed in the detonation process. Conventional rocket engines, for example, must obtain all of their compression from the turbopumps, while the PDE provides additional compression in the combustor. Thus PDE's are expected to achieve higher I(sub sp) than conventional rocket engines and to require smaller turbopumps. The increase in I(sub sp) and the decrease in turbopump capacity must be traded off against each other. Additional advantages include the ability to vary thrust level by adjusting the firing rate rather than throttling the flow through injector elements. The common conclusion derived from these aggregated performance attributes is that PDEs should result in engines which are smaller, lower in cost, and lighter in weight than conventional engines. Unfortunately, the analysis of PDEs is highly complex due to their unsteady operation and non-ideal processes. Although the feasibility of the basic PDE concept has been proven in several experimental and theoretical efforts, the implied performance improvements have yet to be convincingly demonstrated. Also, there are certain developmental issues affecting the practical application of pulse detonation propulsion systems which are yet to be fully resolved. Practical detonation combustion engines, for example, require a repetitive cycle of charge induction, mixing, initiation/propagation of the detonation wave, and expulsion/scavenging of the combustion product gases. Clearly, the performance and power density of such a device depends upon the maximum rate at which this cycle can be successfully implemented. In addition, the electrical energy required for direct detonation initiation can be significant, and a means for direct electrical power production is needed to achieve self-sustained engine operation. This work addresses the technological issues associated

  2. Diminishing detonator effectiveness through electromagnetic effects

    DOEpatents

    Schill, Jr, Robert A.

    2016-09-20

    An inductively coupled transmission line with distributed electromotive force source and an alternative coupling model based on empirical data and theory were developed to initiate bridge wire melt for a detonator with an open and a short circuit detonator load. In the latter technique, the model was developed to exploit incomplete knowledge of the open circuited detonator using tendencies common to all of the open circuit loads examined. Military, commercial, and improvised detonators were examined and modeled. Nichrome, copper, platinum, and tungsten are the detonator specific bridge wire materials studied. The improvised detonators were made typically made with tungsten wire and copper (.about.40 AWG wire strands) wire.

  3. Detonation in TATB Hemispheres

    SciTech Connect

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

    2004-03-17

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

  4. 29 CFR 1926.908 - Use of detonating cord.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... kinks, or angles that direct the cord back toward the oncoming line of detonation. (g) All detonating... direction in which the detonation is to proceed. (j) Detonators for firing the trunkline shall not...

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  6. Chemical Energy Release in Several Recently Discovered Detonation and Deflagration Flows

    NASA Astrophysics Data System (ADS)

    Tarver, Craig M.

    2010-10-01

    Several recent experiments on complex detonation and deflagration flows are analyzed in terms of the chemical energy release required to sustain these flows. The observed double cellular structures in detonating gaseous nitromethane-oxygen and NO2-fuel (H2, CH4, and C2H6) mixtures are explained by the amplification of two distinct pressure wave frequencies by two exothermic reactions, the faster reaction forming vibrationally excited NO* and the slower reaction forming highly vibrationally excited N2**. The establishment of a Chapman-Jouguet (C-J) deflagration behind a weak shock wave, the C-J detonation established after a head-on collision with a shock front, and the C-J detonation conditions established in reactive supersonic flows are quantitatively calculated using the chemical energy release of a H2 + Cl2 mixture. For these three reactive flows, these calculations illustrate that different fractions of the exothermic chemical energy are used to sustain steady-state propagation. C-J detonation calculations on the various initial states using the CHEETAH chemical equilibrium code are shown to be in good agreement with experimental detonation velocity measurements for the head-on collision and supersonic flow detonations.

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

    PubMed

    Gauthier, P; Chaland, F; Masse, L

    2004-11-01

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

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

    PubMed

    Gauthier, P; Chaland, F; Masse, L

    2004-11-01

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

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

    SciTech Connect

    Gauthier, P.; Chaland, F.; Masse, L.

    2004-11-01

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

  10. Pulse Detonation Rocket MHD Power Experiment

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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

  11. DETONATION PRESSURE MEASUREMENTS ON PETN

    SciTech Connect

    Green, L G; Lee, E L

    2006-06-23

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

  12. Gaseous hydrocarbon-air detonations

    SciTech Connect

    Tieszen, S.R.; Stamps, D.W. ); Westbrook, C.K.; Pitz, W.J. )

    1991-04-01

    Detonation cell width measurements were made on mixtures of air and methane, ethane, dimethyl-ether, nitroethane, ethylene, acetylene, propane, 1,2-epoxypropane, n-hexane, 1-nitrohexane, mixed primary hexylnitrate, n-octane, 2,2,4-trimethylpentane, cyclooctane, 1-octene, cis-cyclooctene, 1,7-octadiene, 1-octyne, n-decane, 1,2-epoxydecane, pentyl-ether, and JP4. Cell width measurements were carried out at 25 and 100 {degrees} C for some of these fuel-air mixtures. For the stoichiometric alkanes, alkenes, and alkynes, there is a very slight decrease in the detonation cell width with increasing initial temperature from 25 {degrees} C to 100 {degrees} C, although the differences are within the experimentally uncertainties in cell width measurements. Also within the uncertainty limits of the measurements, there is no variation in detonation cell width with increase fuel molecular weight for n-alkanes from ethane to n-decane. Molecular structure is found to affect detonability for C{sub 8} hydrocarbons, where the saturated ring structure is more sensitive than the straight-chain alkane, which is more sensitive than the branched-chain alkane. Unsaturated alkenes and alkynes are more sensitive to detonation than saturated alkanes.

  13. Deflagration-to-detonation transition in gases in tubes with cavities

    NASA Astrophysics Data System (ADS)

    Smirnov, N. N.; Nikitin, V. F.; Phylippov, Yu. G.

    2010-12-01

    The existence of a supersonic second combustion mode — detonation — discovered by Mallard and Le Chatelier and by Berthélot and Vieille in 1881 posed the question of mechanisms for transition from one mode to the other. In the period 1959-1969, experiments by Salamandra, Soloukhin, Oppenheim, and their coworkers provided insights into this complex phenomenon. Since then, among all the phenomena related to combustion processes, deflagration-to-detonation transition is, undoubtedly, the most intriguing one. Deflagration-to-detonation transition (DDT) in gases is connected with gas and vapor explosion safety issues. Knowing mechanisms of detonation onset control is of major importance for creating effective mitigation measures addressing two major goals: to prevent DDT in the case of mixture ignition, or to arrest the detonation wave in the case where it has been initiated. A new impetus to the increase in interest in deflagration-to-detonation transition processes was given by the recent development of pulse detonation devices. The probable application of these principles to creation of a new generation of engines put the problem of effectiveness of pulse detonating devices at the top of current research needs. The effectiveness of the pulse detonation cycle turned out to be the key factor characterizing the Pulse Detonation Engine (PDE), whose operation modes were shown to be closely related to periodical onset and degeneration of a detonation wave. Those unsteady-state regimes should be self-sustained to guarantee a reliable operation of devices using the detonation mode of burning fuels as a constitutive part of their working cycle. Thus deflagration-to-detonation transition processes are of major importance for the issue. Minimizing the predetonation length and ensuring stability of the onset of detonation enable one to increase the effectiveness of a PDE. The DDT turned out to be the key factor characterizing the PDE operating cycle. Thus, the problem of

  14. Numerical Model of Detonation for Insensitive HE

    NASA Astrophysics Data System (ADS)

    Klimenko, Vladimir

    2011-06-01

    Most of modern munitions are filled by insensitive HE. However, mechanism of initiation of these HE is still unknown. IHE have not any pores and, therefore, hot spot mechanism does not work here. What is a mechanism working in this case? We have used 3D hydrocode to study process of shock wave loading of mixture of HMX grains with different binders (HMX/binder=88/12) and have determined formation of surface layers with increased plastic deformation. According to the dislocation mechanism of detonation (V. Klimenko, I. Kozyreva, J. Energetic Materials, 2010, v. 28, pp. 249-262) plastic deformation generates definite concentration of radicals. Surface layers have also increased temperature due to viscous work. So, these activated layers have increased temperature and number of radicals in comparison with values inside grains. Kinetic calculation has shown fast decomposition of these layers. As a result, the activated layer is ignited and this gives beginning of grain burning process. The developed two-stages mechanism has been incorporated into 2D hydrocode. The developed numerical model demonstrates high accuracy in simulation of detonation processes in IHE (in particular, PBXN-110 and B2241).

  15. Near-limit propagation of gaseous detonations in narrow annular channels

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    New results on the near-limit behaviors of gaseous detonations in narrow annular channels are reported in this paper. Annular channels of widths 3.2 and 5.9 mm were made using circular inserts in a 50.8 mm-diameter external tube. The length of each annular channel was 1.8 m. Detonations were initiated in a steel driver tube where a small volume of a sensitive C2H2+ 2.5O2 mixture was injected to facilitate detonation initiation. A 2 m length of circular tube with a 50.8 mm diameter preceded the annular channel so that a steady Chapman-Jouguet (CJ) detonation was established prior to entering the annular channel. Four detonable mixtures of C2H2 {+} 2.5O2 {+} 85 % Ar, C2H2 {+} 2.5O2 {+} 70 % Ar, C3H8 {+} 5O2 , and CH4 {+} 2O2 were used in the present study. Photodiodes spaced 10 cm throughout the length of both the annular channel and circular tube were used to measure the detonation velocity. In addition, smoked foils were inserted into the annular channel to monitor the cellular structure of the detonation wave. The results show that, well within the detonability limits, the detonation wave propagates along the channel with a small local velocity fluctuation and an average global velocity can be deduced. The average detonation velocity has a small deficit of 5-15 % far from the limits and the velocity rapidly decreases to 0.7V_{CJ} -0.8V_{CJ} when the detonation propagates near the limit. Subsequently, the fluctuation of local velocity also increases as the decreasing initial pressure approaches the limit. In the two annular channels used in this work, no galloping detonations were observed for both the stable and unstable mixtures tested. The present study also confirms that single-headed spinning detonation occurs at the limit, as in a circular tube, rather than the up and down "zig zag" mode in a two-dimensional, rectangular channel.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    SciTech Connect

    Klemens, R.; Kapuscinski, M.; Wolinski, M.; Wolanski, P. . Instytut Techniki Cieplnej); Sichel, M. . Dept. of Aerospace Engineering)

    1994-12-01

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

  18. Development of a Detonation Profile Test for Studying Aging Effects in LX-17

    SciTech Connect

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

    2002-03-25

    A new small-scale Detonation Profile Test (DPT) is being developed to investigate aging effects on the detonation behavior of insensitive high explosives. The experiment involves initiating a small LX-17 cylindrical charge (12.7-19.1 mm diameter x 25.4-33 mm long) and measuring the velocity and curvature of the emerging detonation wave using a streak camera. Results for 12.7 mm diameter unconfined LX-17 charges show detonation velocity in the range between 6.79 and 7.06 km/s for parts up to 33 mm long. Since LX-17 can not sustain detonation at less than 7.3 km/s, these waves were definitely failing. Experiments with confined 12.7 mm diameter and unconfined 19.1 mm diameter samples showed wave velocities in the range of 7.4-7.6 km/s, values approaching steady state conditions at infinite diameter. Experiments with unconfined 19.1 mm diameter specimens are expected to provide reproducible and useful range of detonation parameters suitable for studying aging effects.

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

    NASA Technical Reports Server (NTRS)

    Powers, Joseph M.; Gonthier, Keith A.

    1992-01-01

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

  20. Detonation Jet Engine. Part 1--Thermodynamic Cycle

    ERIC Educational Resources Information Center

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    We present the most relevant works on jet engine design that utilize thermodynamic cycle of detonative combustion. The efficiency advantages of thermodynamic detonative combustion cycle over Humphrey combustion cycle at constant volume and Brayton combustion cycle at constant pressure were demonstrated. An ideal Ficket-Jacobs detonation cycle, and…

  1. Rotating Detonation Combustion: A Computational Study for Stationary Power Generation

    NASA Astrophysics Data System (ADS)

    Escobar, Sergio

    The increased availability of gaseous fossil fuels in The US has led to the substantial growth of stationary Gas Turbine (GT) usage for electrical power generation. In fact, from 2013 to 2104, out of the 11 Tera Watts-hour per day produced from fossil fuels, approximately 27% was generated through the combustion of natural gas in stationary GT. The thermodynamic efficiency for simple-cycle GT has increased from 20% to 40% during the last six decades, mainly due to research and development in the fields of combustion science, material science and machine design. However, additional improvements have become more costly and more difficult to obtain as technology is further refined. An alternative to improve GT thermal efficiency is the implementation of a combustion regime leading to pressure-gain; rather than pressure loss across the combustor. One concept being considered for such purpose is Rotating Detonation Combustion (RDC). RDC refers to a combustion regime in which a detonation wave propagates continuously in the azimuthal direction of a cylindrical annular chamber. In RDC, the fuel and oxidizer, injected from separated streams, are mixed near the injection plane and are then consumed by the detonation front traveling inside the annular gap of the combustion chamber. The detonation products then expand in the azimuthal and axial direction away from the detonation front and exit through the combustion chamber outlet. In the present study Computational Fluid Dynamics (CFD) is used to predict the performance of Rotating Detonation Combustion (RDC) at operating conditions relevant to GT applications. As part of this study, a modeling strategy for RDC simulations was developed. The validation of the model was performed using benchmark cases with different levels of complexity. First, 2D simulations of non-reactive shock tube and detonation tubes were performed. The numerical predictions that were obtained using different modeling parameters were compared with

  2. Slag Characterization and Removal Using Pulse Detonation for Coal Gasification.

    SciTech Connect

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

    1997-09-25

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

  3. Equation of state for detonation products. [Detonation products

    SciTech Connect

    Davis, W.C.

    1985-01-01

    The concepts of hydrodynamics and thermodynamics as they apply to equations of state for explosive products are collected and discussed. The physics behind the behavior of dense gases is considered. Some ideas about applications are presented. This paper is intended as an introduction to the subject of equation of state for detonation products. 7 references, 3 figures.

  4. Effects of high activation energies on acoustic timescale detonation initiation

    NASA Astrophysics Data System (ADS)

    Regele, J. D.; Kassoy, D. R.; Vasilyev, O. V.

    2012-08-01

    Acoustic timescale Deflagration-to-Detonation Transition (DDT) has been shown to occur through the generation of compression waves emitted by a hot spot or reaction centre where the pressure and temperature increase with little diminution of density. In order to compensate for the multi-scale nature of the physico-chemical processes, previous numerical simulations in this area have been limited to relatively small activation energies. In this work, a computational study investigates the effect of increased activation energy on the time required to form a detonation wave and the change in behaviour of each hot spot as the activation energy is increased. The simulations use a localised spatially distributed thermal power deposition of limited duration into a finite volume of reactive gas to facilitate DDT. The Adaptive Wavelet-Collocation Method is used to solve efficiently the 1-D reactive Euler equations with one-step Arrhenius kinetics. The DDT process as described in previous work is characterised by the formation of hot spots during an initial transient period, explosion of the hot spots and creation of an accelerating reaction front that reaches the lead shock and forms an overdriven detonation wave. Current results indicate that as the activation energy is raised the chemical heat release becomes more temporally distributed. Hot spots that produce an accelerating reaction front with low activation energies change behaviour with increased activation energy so that no accelerating reaction front is created. An acoustic timescale ratio is defined that characterises the change in behaviour of each hot spot.

  5. Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector

    NASA Technical Reports Server (NTRS)

    Santoro, Robert J.; Pal, Sibtosh

    2005-01-01

    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.

  6. Experimental Study of a Pulse Detonation Engine Driven Ejector

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  7. Multi-Level Analysis of Pulsed Detonation Engines

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    The present study explores some issues concerning the operational performance of pulsed detonation engines. Zero-, one- and two-dimensional, transient models are employed in a synergistic manner to elucidate the various characteristics that can be expected from each level of analysis. The zero-dimensional model provides rapid parametric trends that help to identify the global characteristics of pulsed detonation engines. The one-dimensional model adds key wave propagation issues that are omitted in the zero-dimensional model and helps to assess its limitations. Finally, the two-dimensional model allows estimates of the first-order multi-dimensional effects and provides an initial multi-dimensional end-correction for the one-dimensional model. The zero-dimensional results indicate that the pulsed detonation engine is competitive with a rocket engine when exhausting to vacuum conditions. At finite back pressures, the PDE out-performs the rocket if the combustion pressure rise from the detonation is added to the chamber pressure in the rocket. If the two peak pressures are the same, the rocket performance is higher. Two-dimensional corrections added to the one-dimensional model result in a modest improvement in predicted specific impulse over the constant pressure boundary condition.

  8. Environmentally Benign Stab Detonators

    SciTech Connect

    Gash, A E

    2006-07-07

    The coupling of energetic metallic multilayers (a.k.a. flash metal) with energetic sol-gel synthesis and processing is an entirely new approach to forming energetic devices for several DoD and DOE needs. They are also practical and commercially viable manufacturing techniques. Improved occupational safety and health, performance, reliability, reproducibility, and environmentally acceptable processing can be achieved using these methodologies and materials. The development and fielding of this technology will enhance mission readiness and reduce the costs, environmental risks and the necessity of resolving environmental concerns related to maintaining military readiness while simultaneously enhancing safety and health. Without sacrificing current performance, we will formulate new impact initiated device (IID) compositions to replace materials from the current composition that pose significant environmental, health, and safety problems associated with functions such as synthesis, material receipt, storage, handling, processing into the composition, reaction products from testing, and safe disposal. To do this, we will advance the use of nanocomposite preparation via the use of multilayer flash metal and sol-gel technologies and apply it to new small IIDs. This work will also serve to demonstrate that these technologies and resultant materials are relevant and practical to a variety of energetic needs of DoD and DOE. The goal will be to produce an IID whose composition is acceptable by OSHA, EPA, the Clean Air Act, Clean Water Act, Resource Recovery Act, etc. standards, without sacrificing current performance. The development of environmentally benign stab detonators and igniters will result in the removal of hazardous and toxic components associated with their manufacturing, handling, and use. This will lead to improved worker safety during manufacturing as well as reduced exposure of Service personnel during their storage and or use in operations. The

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

    SciTech Connect

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

    2012-01-01

    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.

  10. Sensitized Liquid Hydrazine Detonation Studies

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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.

  11. Airbreathing Pulse Detonation Engine Performance

    NASA Technical Reports Server (NTRS)

    Povinelli, Louis A.; Yungster, Shaye

    2002-01-01

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

  12. Airbreathing Pulse Detonation Engine Performance

    NASA Technical Reports Server (NTRS)

    Povinelli, Louis A.; Yungster, Shaye

    2002-01-01

    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.

  13. Pulse detonation engines and components thereof

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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.

  14. Development of a Gas-Fed Pulse Detonation Research Engine

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  15. Effect of Velocity of Detonation of Explosives on Seismic Radiation

    NASA Astrophysics Data System (ADS)

    Stroujkova, A. F.; Leidig, M.; Bonner, J. L.

    2014-12-01

    We studied seismic body wave generation from four fully contained explosions of approximately the same yields (68 kg of TNT equivalent) conducted in anisotropic granite in Barre, VT. The explosions were detonated using three types of explosives with different velocities of detonation (VOD): Black Powder (BP), Ammonium Nitrate Fuel Oil/Emulsion (ANFO), and Composition B (COMP B). The main objective of the experiment was to study differences in seismic wave generation among different types of explosives, and to determine the mechanism responsible for these differences. The explosives with slow burn rate (BP) produced lower P-wave amplitude and lower corner frequency, which resulted in lower seismic efficiency (0.35%) in comparison with high burn rate explosives (2.2% for ANFO and 3% for COMP B). The seismic efficiency estimates for ANFO and COMP B agree with previous studies for nuclear explosions in granite. The body wave radiation pattern is consistent with an isotropic explosion with an added azimuthal component caused by vertical tensile fractures oriented along pre-existing micro-fracturing in the granite, although the complexities in the P- and S-wave radiation patterns suggest that more than one fracture orientation could be responsible for their generation. High S/P amplitude ratios and low P-wave amplitudes suggest that a significant fraction of the BP source mechanism can be explained by opening of the tensile fractures as a result of the slow energy release.

  16. Slang characterization and removal using pulse detonation technology during coal gasification

    SciTech Connect

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

    1997-03-25

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

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

    SciTech Connect

    Moll, R.; Woosley, S. E.

    2013-09-10

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

  18. Numerical simulation of detonation reignition in H 2-O 2 mixtures in area expansions

    NASA Astrophysics Data System (ADS)

    Jones, D. A.; Kemister, G.; Tonello, N. A.; Oran, E. S.; Sichel, M.

    Time-dependent, two-dimensional, numerical simulations of a transmitted detonation show reignition occuring by one of two mechanisms. The first mechanism involves the collision of triple points as they expand along a decaying shock front. In the second mechanism ignition results from the coalescence of a number of small, relatively high pressure regions left over from the decay of weakened transverse waves. The simulations were performed using an improved chemical kinetic model for stoichiometric H 2-O 2 mixtures. The initial conditions were a propagating, two-dimensional detonation resolved enough to show transverse wave structure. The calculations provide clarification of the reignition mechanism seen in previous H 2-O 2-Ar simulations, and again demonstrate that the transverse wave structure of the detonation front is critical to the reignition process.

  19. Investigation of detonation velocity in heterogeneous explosive system using the reactive Burgers' analog

    NASA Astrophysics Data System (ADS)

    Di Labbio, G.; Kiyanda, C. B.; Mi, X.; Higgins, A. J.; Nikiforakis, N.; Ng, H. D.

    2016-06-01

    In this study, the applicability of the Chapman-Jouguet (CJ) criterion is tested numerically for heterogeneous explosive media using a simple detonation analog. The analog system consists of a reactive Burgers' equation coupled with an Arrhenius type reaction wave, and the heterogeneity of the explosive media is mimicked using a discrete energy source approach. The governing equation is solved using a second order, finite-volume approach and the average propagation velocity of the discrete detonation is determined by tracking the leading shock front. Consistent with previous studies, the averaged velocity of the leading shock front from the unsteady numerical simulations is also found to be in good agreement with the velocity of a CJ detonation in a uniform medium wherein the energy source is spatially homogenized. These simulations have thus implications for whether the CJ criterion is valid to predict the detonation velocity in heterogeneous explosive media.

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

    NASA Astrophysics Data System (ADS)

    Schwer, Douglas

    2011-11-01

    Rotating detonation engines (RDE's) represent a natural extension of the extensively studied pulse detonation engines (PDE's) for obtaining propulsion from the high efficiency detonation cycle. RDE's require fuel and oxidizer under high pressure to be injected through micro-nozzles from one or two plenums (for premixed and non-premixed). This injection process is critically important to the stability and performance of the RDE. This paper studies the effect of this injection process on the detonation wave within the combustion chamber, with an emphasis on how the fluid dynamics are affected. Both two-dimensional and three-dimensional simulations are done using well proven numerical methods for both the combustion chamber and mixture plenums of an idealized RDE. This work is supported through NRL 6.1 Computational Physics Task Area

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

    SciTech Connect

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

    2013-07-01

    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

  2. Numerical study of detonation transmission in mixtures containing chemical inhibitors

    NASA Astrophysics Data System (ADS)

    Papalexandris, M. V.

    2012-05-01

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

  3. Dynamics of galloping detonations: inert hydrodynamics with pulsed energy release

    NASA Astrophysics Data System (ADS)

    Radulescu, Matei I.; Shepherd, Joseph E.

    2015-11-01

    Previous models for galloping and cellular detonations of Ulyanitski, Vasil'ev and Higgins assume that the unit shock decay or cell can be modeled by Taylor-Sedov blast waves. We revisit this concept for galloping detonations, which we model as purely inert hydrodynamics with periodically pulsed energy deposition. At periodic time intervals, the chemical energy of the non-reacted gas accumulating between the lead shock and the contact surface separating reacted and non reacted gas is released nearly instantaneously. In between these pulses, the gas evolves as an inert medium. The resulting response of the gas to the periodic forcing is a sudden gain in pressure followed by mechanical relaxation accompanied by strong shock waves driven both forward and backwards. It is shown that the decay of the lead shock in-between pulses follows an exponential decay, whose time constant is controlled by the frequency of the energy deposition. More-over, the average speed of the lead shock is found to agree within 2 percent to the ideal Chapman-Jouguet value, while the large scale dynamics of the wave follows closely the ideal wave form of a CJ wave trailed by a Taylor expansion. When friction and heat losses are accounted for, velocity deficits are predicted, consistent with experiment. Work performed while MIR was on sabbatical at Caltech.

  4. a New Approach of the Deflagration to Detonation Transition in SNIa Thermonuclear Supernovae

    NASA Astrophysics Data System (ADS)

    Chièze, Jean Pierre; Charignon, Camille

    2015-03-01

    A wide class of type Ia thermonuclear supernovae models relies on the transition from the subsonic deflagration combustion regime to the supersonic detonation regime of the carbon and oxygen mixture of an accreting white dwarf, near the Chandrasekhar mass. We show that this can actually be achieved in a cold C+O white dwarf near the Chandrasekhar mass, with seed sound waves of relatively low Mach number M ˜ 0.02. Moreover, even weaker perturbations, with velocity perturbations as low as M ˜ 0.003 can trigger a detonation wave in SNIa progenitors models wich include the presence of a thin helium surface layer.

  5. A fast, low resistance switch for small slapper detonators

    NASA Astrophysics Data System (ADS)

    Richardson, D. D.; Jones, D. A.

    1986-10-01

    A novel design for a shock compression conduction switch for use with slapper detonators is described. The switch is based on the concept of an explosively driven flyer plate impacting a plastic insulator and producing sufficient pressure within the insulator to produce a conduction transition. An analysis of the functioning of the switch is made using a simple Gurney model for the explosive, and basic shock wave theory to calculate impact pressure and switch closure times. The effect of explosive tamping is considered, and calculations are carried out for two donor explosive thicknesses and a range of flyer plate thicknesses. The new switch has been successfully tested in a series of experimental slapper detonator firings. The results of these tests show trends in overall agreement with those predicted by the calculations.

  6. Modeling of Multi-Tube Pulse Detonation Engine Operation

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  7. Non-detonable explosive simulators

    DOEpatents

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

    1994-11-01

    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.

  8. Non-detonable explosive simulators

    DOEpatents

    Simpson, Randall L.; Pruneda, Cesar O.

    1994-01-01

    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.

  9. Improved detonation modeling with CHEETAH

    SciTech Connect

    Heller, A.

    1997-11-01

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

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

    SciTech Connect

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

    2002-05-02

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

  11. Optically triggered fire set/detonator system

    DOEpatents

    Chase, Jay B.; Pincosy, Philip A.; Chato, Donna M.; Kirbie, Hugh; James, Glen F.

    2007-03-20

    The present invention is directed to a system having a plurality of capacitor discharge units (CDUs) that includes electrical bridge type detonators operatively coupled to respective explosives. A pulse charging circuit is adapted to provide a voltage for each respective capacitor in each CDU. Such capacitors are discharged through the electrical bridge type detonators upon receiving an optical signal to detonate respective operatively coupled explosives at substantially the same time.

  12. Deflagrations and detonations in thermonuclear supernovae.

    PubMed

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

    2004-05-28

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

  13. Laser diode initiated detonators for space applications

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  14. Deflagrations and detonations in thermonuclear supernovae.

    PubMed

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

    2004-05-28

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

  15. Radioactive Fallout from Terrorist Nuclear Detonations

    SciTech Connect

    Marrs, R E

    2007-05-03

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

  16. Critical diameter and spin effects in detonation of cast and liquid explosives

    SciTech Connect

    Kozak, G.D.

    1995-09-01

    Results of experimental measurement of critical diameter d{sub cr}, of cast charges of TNT/RDX, TNT/potassium picrate, TNT/PETN, and liquid solutions of dinitrotoluene in bisnitroxyethylnitramine are presented. The data obtained are compared with the results of previous investigations of spin detonation waves in the systems under consideration. For both TNT-based cast charges and liquid mixtures, the domains were registered on the dependence of critical diameter on content in which d{sub cr} remained invariant. These areas coincide with the range of sensitizer content in the mixtures in which spin phenomena are observed. Experimental results corroborate a previous conclusion that spin waves favor spreading of the general detonation process in cast systems and prevent detonation of liquid explosives.

  17. Shock-to-detonation transition of RDX and NTO based composite high explosives: experiments and modeling

    NASA Astrophysics Data System (ADS)

    Baudin, Gerard; Roudot, Marie; Genetier, Marc

    2013-06-01

    Composite HMX and NTO based high explosives (HE) are widely used in ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside HE. Comparing to a pressed HE, a composite HE is not porous and the hot-spots are mainly located at the grain - binder interface leading to a different behavior during shock-to-detonation transition. An investigation of how shock-to-detonation transition occurs inside composite HE containing RDX and NTO is proposed in this lecture. Two composite HE have been studied. The first one is HMX - HTPB 82:18. The second one is HMX - NTO - HTPB 12:72:16. These HE have been submitted to plane sustained shock waves at different pressure levels using a laboratory powder gun. Pressure signals are measured using manganin gauges inserted at several distances inside HE. The corresponding run-distances to detonation are determined using wedge test experiments where the plate impact is performed using a powder gun. Both HE exhibit a single detonation buildup curve in the distance - time diagram of shock-to-detonation transition. This feature seems a common shock-to-detonation behavior for composite HE without porosity. This behavior is also confirmed for a RDX - HTPB 85:15 based composite HE. Such a behavior is exploited to determine the heterogeneous reaction rate versus the shock pressure using a method based on the Cauchy-Riemann problem inversion. The reaction rate laws obtained allow to compute both run-distance to detonation and pressure signals.

  18. Equations of state of detonation products: ammonia and methane

    NASA Astrophysics Data System (ADS)

    Lang, John; Dattelbaum, Dana; Goodwin, Peter; Garcia, Daniel; Coe, Joshua; Leiding, Jeffery; Gibson, Lloyd; Bartram, Brian

    2015-06-01

    Ammonia (NH3) and methane (CH4) are two principal product gases resulting from explosives detonation, and the decomposition of other organic materials under shockwave loading (such as foams). Accurate thermodynamic descriptions of these gases are important for understanding the detonation performance of high explosives. However, shock compression data often do not exist for molecular species in the dense gas phase, and are limited in the fluid phase. Here, we present equation of state measurements of elevated initial density ammonia and methane gases dynamically compressed in gas-gun driven plate impact experiments. Pressure and density of the shocked gases on the principal Hugoniot were determined from direct particle velocity and shock wave velocity measurements recorded using optical velocimetry (Photonic Doppler velocimetry (PDV) and VISAR (velocity interferometer system for any reflector)). Streak spectroscopy and 5-color pyrometry were further used to measure the emission from the shocked gases, from which the temperatures of the shocked gases were estimated. Up to 0.07 GPa, ammonia was not observed to ionize, with temperature remaining below 7000 K. These results provide quantitative measurements of the Hugoniot locus for improving equations of state models of detonation products.

  19. Detonation diffraction through different geometries

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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 · λ (with λ 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/ λ. 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/λ. 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/ λ 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/ λ as 2.2 whatever the intermediate diameter D is. This configuration provides a significant improvement in the detonation transmission conditions.

  20. Diagnostics for slapper detonator systems

    SciTech Connect

    Boberg, R.E.; Lee, R.E.; Lee, R.S.; Von Holle, W.

    1989-03-28

    This report discusses diagnostics which have been used to evaluate CDU characteristics and performance, slapper characteristics and performance and the response of a HE detonator output pellet to a slapper stimulus. Many of the diagnostics discussed are appropriate for development and production testing. These include CVR current measurements, voltage probe measurements, time-of-flight measurements, threshold measurements, function time measurements, use of steel witness plates and determination of design margin. Some of the more-sophisticated, expensive diagnostics discussed have yielded very useful information, but are not required for development and production testing. 8 refs., 9 figs., 1 tab.

  1. Detonation transfer understanding applied to aerospace problems

    NASA Technical Reports Server (NTRS)

    Schimmel, M. L.

    1974-01-01

    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.

  2. Using Schlieren Visualization to Track Detonator Performance

    NASA Astrophysics Data System (ADS)

    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

    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.

  3. 14 CFR 33.47 - Detonation test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Detonation test. 33.47 Section 33.47 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.47 Detonation test. Each...

  4. 14 CFR 33.47 - Detonation test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Detonation test. 33.47 Section 33.47 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.47 Detonation test. Each...

  5. 14 CFR 33.47 - Detonation test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Detonation test. 33.47 Section 33.47 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.47 Detonation test. Each...

  6. Detonation in tungsten-loaded HMX

    SciTech Connect

    Goldstein, S.; Mader, C.L.

    1985-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Wilson, Jack; Paxson, Daniel E.

    2002-01-01

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

  8. Exhaust Nozzle for a Multitube Detonative Combustion Engine

    NASA Technical Reports Server (NTRS)

    Bratkovich, Thomas E.; Williams, Kevin E.; Bussing, Thomas R. A.; Lidstone, Gary L.; Hinkey, John B.

    2004-01-01

    An improved type of exhaust nozzle has been invented to help optimize the performances of multitube detonative combustion engines. The invention is applicable to both air-breathing and rocket engines used to propel some aircraft and spacecraft, respectively. In a detonative combustion engine, thrust is generated through the expulsion of combustion products from a detonation process in which combustion takes place in a reaction zone coupled to a shock wave. The combustion releases energy to sustain the shock wave, while the shock wave enhances the combustion in the reaction zone. The coupled shockwave/reaction zone, commonly referred to as a detonation, propagates through the reactants at very high speed . typically of the order of several thousands of feet per second (of the order of 1 km/s). The very high speed of the detonation forces combustion to occur very rapidly, thereby contributing to high thermodynamic efficiency. A detonative combustion engine of the type to which the present invention applies includes multiple parallel cylindrical combustion tubes, each closed at the front end and open at the rear end. Each tube is filled with a fuel/oxidizer mixture, and then a detonation wave is initiated at the closed end. The wave propagates rapidly through the fuel/oxidizer mixture, producing very high pressure due to the rapid combustion. The high pressure acting on the closed end of the tube contributes to forward thrust. When the detonation wave reaches the open end of the tube, it produces a blast wave, behind which the high-pressure combustion products are expelled from the tube. The process of filling each combustion tube with a detonable fuel/oxidizer mixture and then producing a detonation repeated rapidly to obtain repeated pulses of thrust. Moreover, the multiple combustion tubes are filled and fired in a repeating sequence. Hence, the pressure at the outlet of each combustion tube varies cyclically. A nozzle of the present invention channels the

  9. A novel method for the measurement of the von Neumann spike in detonating high explosives

    NASA Astrophysics Data System (ADS)

    Sollier, A.; Bouyer, V.; Hébert, P.; Doucet, M.

    2016-06-01

    We present detonation wave profiles measured in T2 (97 wt. % TATB) and TX1 (52 wt. % TATB and 45 wt. % HMX) high explosives. The experiments consisted in initiating a detonation wave in a 15 mm diameter cylinder of explosive using an explosive wire detonator and an explosive booster. Free surface velocity wave profiles were measured at the explosive/air interface using a Photon Doppler Velocimetry system. We demonstrate that a comparison of these free surface wave profiles with those measured at explosive/window interfaces in similar conditions allows to bracket the von Neumann spike in a narrow range. For T2, our measurements show that the spike pressure lies between 35.9 and 40.1 GPa, whereas for TX1, it lies between 42.3 and 47.0 GPa. The numerical simulations performed in support to these measurements show that they can be used to calibrate reactive burn models and also to check the accuracy of the detonation products equation of state at low pressure.

  10. Electrostatic discharge effects on EBW detonators

    SciTech Connect

    Lee, R S; Lee, R E

    1991-04-01

    With appropriate circuit resistance and inductance and sufficient stored energy, discharging a charged human body or component through an exploding bridgewire (EBW) detonator may cause the detonator to function or may damage the detonator. We have studied the effects of electrostatic discharge (ESD) on a number of exploding bridgewire detonators which were subjected to discharges which passed directly through the bridgewires (pin-to-pin), as well as discharges which passed from the bridge to the metal case of the detonator (pin-to-case). We have performed calculations to determine the values of inductance and resistance for which burst and melt may occur for given ESD sources, using a phenomenological model of bridgewire burst in a computer code called FIRESET. Bridge melt was computed using the same computer code, but using experimental values of bridge resistivity and specific heat up to melt. 13 refs., 5 figs.

  11. Performance characterization of the NASA standard detonator

    SciTech Connect

    Tarbell, W.W.; Burke, T.L.; Solomon, S.E.

    1995-05-01

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

  12. Pulse detonation assembly and hybrid engine

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2013-09-01

    Influence of ambient pressure on energy conversion efficiency from a Nd : glass laser pulse (λ = 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 ηbw 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 (λ = 10.6 µm), higher fraction absorption in the laser supported detonation regime ηLSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ηbw/ηLSD≈90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case.

  14. Efficiency of Pulsed Detonation Thermal Spraying

    NASA Astrophysics Data System (ADS)

    Cannon, Jacob E.; Alkam, Mohammad; Butler, P. Barry

    2008-12-01

    Pulsed detonation thermal spray coating is used to enhance the material properties at the surface of an object. The present research implements computational fluid dynamic modeling to identify the efficiency of energy and mass delivered to potential target locations. Six cases of a hydrogen-air mixture are used to investigate the gas flow from the instant of ignition to the instant of flow reversal at the tube exit. Flow monitors are included in the model to represent potential target locations. These monitors are placed at different axial locations in order to record mass flow rate and the flow rate of enthalpy over time. The results indicate that there exists a quasi-steady jet that is efficient and predictable in delivery of energy and mass from the tube exit to potential target locations positioned on the centerline. The duration of the quasi-steady jet is dependent on the fraction of combustible gas (i.e., % fill). Much of the initial energy and mass delivered from the jet avoids the flow monitors. This is found to be related to the evolution of the jet behind the blast wave where energy is lost in expansion and vorticity production. It is also found that nearly 11-18% of the available energy and 20-23% of the available mass remains in the tube after flow reversal.

  15. Nonideal detonation regimes in low density explosives

    NASA Astrophysics Data System (ADS)

    Ershov, A. P.; Kashkarov, A. O.; Pruuel, E. R.; Satonkina, N. P.; Sil'vestrov, V. V.; Yunoshev, A. S.; Plastinin, A. V.

    2016-02-01

    Measurements using Velocity Interferometer System for Any Reflector (VISAR) were performed for three high explosives at densities slightly above the natural loose-packed densities. The velocity histories at the explosive/window interface demonstrate that the grain size of the explosives plays an important role. Fine-grained materials produced rather smooth records with reduced von Neumann spike amplitudes. For commercial coarse-grained specimens, the chemical spike (if detectable) was more pronounced. This difference can be explained as a manifestation of partial burn up. In fine-grained explosives, which are more sensitive, the reaction can proceed partly within the compression front, which leads to a lower initial shock amplitude. The reaction zone was shorter in fine-grained materials because of higher density of hot spots. The noise level was generally higher for the coarse-grained explosives, which is a natural stochastic effect of the highly non-uniform flow of the heterogeneous medium. These results correlate with our previous data of electrical conductivity diagnostics. Instead of the classical Zel'dovich-von Neumann-Döring profiles, violent oscillations around the Chapman-Jouguet level were observed in about half of the shots using coarse-grained materials. We suggest that these unusual records may point to a different detonation wave propagation mechanism.

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

    SciTech Connect

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

    1996-10-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  18. NUCLEOSYNTHESIS IN TWO-DIMENSIONAL DELAYED DETONATION MODELS OF TYPE Ia SUPERNOVA EXPLOSIONS

    SciTech Connect

    Maeda, K.; Roepke, F.K.; Fink, M.; Hillebrandt, W.; Travaglio, C.; Thielemann, F.-K.

    2010-03-20

    For the explosion mechanism of Type Ia supernovae (SNe Ia), different scenarios have been suggested. In these, the propagation of the burning front through the exploding white dwarf (WD) star proceeds in different modes, and consequently imprints of the explosion model on the nucleosynthetic yields can be expected. The nucleosynthetic characteristics of various explosion mechanisms are explored based on three two-dimensional explosion simulations representing extreme cases: a pure turbulent deflagration, a delayed detonation following an approximately spherical ignition of the initial deflagration, and a delayed detonation arising from a highly asymmetric deflagration ignition. Apart from this initial condition, the deflagration stage is treated in a parameter-free approach. The detonation is initiated when the turbulent burning enters the distributed burning regime. This occurs at densities around 10{sup 7} g cm{sup -3}-relatively low as compared to existing nucleosynthesis studies for one-dimensional spherically symmetric models. The burning in these multidimensional models is different from that in one-dimensional simulations as the detonation wave propagates both into unburned material in the high-density region near the center of a WD and into the low-density region near the surface. Thus, the resulting yield is a mixture of different explosive burning products, from carbon-burning products at low densities to complete silicon-burning products at the highest densities, as well as electron-capture products synthesized at the deflagration stage. Detailed calculations of the nucleosynthesis in all three models are presented. In contrast to the deflagration model, the delayed detonations produce a characteristic layered structure and the yields largely satisfy constraints from Galactic chemical evolution. In the asymmetric delayed detonation model, the region filled with electron capture species (e.g., {sup 58}Ni, {sup 54}Fe) is within a shell, showing a large off

  19. Detonator comprising a nonlinear transmission line

    SciTech Connect

    Elizondo-Decanini, Juan M

    2014-12-30

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

  20. Eigenvalue Detonation of Combined Effects Aluminized Explosives

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  1. Premature detonation problem. [Artillery shells

    SciTech Connect

    Pimbley, G.H.; Marshall, E.F.

    1980-05-01

    Determining how cavities or voids in the explosive loads of artillery shells cause in-bore premature detonations is important to military authorities. Though answers continue to be elusive, in detailing recent studies of the problem at LASL, some traditional approaches were examined and a new direction of investigation is suggested. The aquarium experiment and the pipe test were devised at LASL to model the events taking place in a base gap, or in an internal cavity, in the load of an accelerating artillery shell. Numerical simulation was used to assess the data from these experiments. Both the experimental and the numerical simulation phases of the project are described. The commonly accepted gas compression, thermal ignition mechanism is not consistent with the results of this study. The dominant mechanism or mechanisms have not been identified.

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

    SciTech Connect

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

    2009-06-26

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

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

    SciTech Connect

    Stewart, D.S.

    1999-07-01

    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.

  4. Development of Detonation Modeling Capabilities for Rocket Test Facilities: Hydrogen-Oxygen-Nitrogen Mixtures

    NASA Technical Reports Server (NTRS)

    Allgood, Daniel C.

    2016-01-01

    The objective of the presented work was to develop validated computational fluid dynamics (CFD) based methodologies for predicting propellant detonations and their associated blast environments. Applications of interest were scenarios relevant to rocket propulsion test and launch facilities. All model development was conducted within the framework of the Loci/CHEM CFD tool due to its reliability and robustness in predicting high-speed combusting flow-fields associated with rocket engines and plumes. During the course of the project, verification and validation studies were completed for hydrogen-fueled detonation phenomena such as shock-induced combustion, confined detonation waves, vapor cloud explosions, and deflagration-to-detonation transition (DDT) processes. The DDT validation cases included predicting flame acceleration mechanisms associated with turbulent flame-jets and flow-obstacles. Excellent comparison between test data and model predictions were observed. The proposed CFD methodology was then successfully applied to model a detonation event that occurred during liquid oxygen/gaseous hydrogen rocket diffuser testing at NASA Stennis Space Center.

  5. Double-HE-Layer Detonation-Confinement Sandwich Tests: The Effect of Slow-Layer Density

    NASA Astrophysics Data System (ADS)

    Hill, Larry

    2013-06-01

    Over a period of several years, we have explored the phenomenon in which slabs of high explosives (HEs) with differing detonation speeds are joined along one of their faces. Both are initiated (usually by a line-wave generator) at one edge. If there were no coupling between the layers, the detonation in the fast HE would outrun that in the slow HE. In reality, the detonation in the fast HE transmits an oblique shock into the slow HE, the phase speed of which is equal to the speed of the fast HE. This has one of two effects depending on the particulars. First, the oblique shock transmitted to the slow HE can pre-shock and deaden it, extinguishing the detonation in the slow HE. Second, the oblique shock can transversely initiate the slow layer, pulling its detonation along at the fast HE speed. When the second occurs, it does so at the ``penalty'' of a nominally dead layer, which forms in the slow HE adjacent to the material interface. We present the results of tests in which the fast layer was 3-mm-thick PBX 9501 (95 wt% HMX), and the slow layer was 8-mm-thick PBX 9502 (95 wt% TATB). The purpose was to observe the effect of slow layer density on the ``dead'' layer thickness. Very little effect was observed across the nominal PBX 9502 density range, 1.885-1.895 g/cc.

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

    NASA Astrophysics Data System (ADS)

    Kindracki, J.

    2014-11-01

    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.

  7. Determination of minimum mass and spatial location of initiator for detonation of propylene oxide aerosols

    NASA Astrophysics Data System (ADS)

    Apparao, A.; Saji, J.; Balaji, M.; Devangan, A. K.; Rao, C. R.

    2016-06-01

    The mishandling of liquid fuels during production, processing or transportation can lead to the formation of combustible two-phase mixtures. These mixtures, with the availability of a suitable energy source, may be ignited generating a deflagration, or even a detonation wave. For military applications, unconfined fuel aerosols are created and detonated with the help of a strong shock generated by a powerful energy source. The minimum energy requirement is expressed in terms of the shock strength, or mass of the high-explosive-based initiator. In this study, the detonability of unconfined aerosols of 4.3 kg propylene oxide was studied by positioning different quantities of cylindrical-shaped initiators of RDX/wax (95/5) at a fixed spatial location in the aerosol cloud, and the minimum mass of the initiator required for detonation initiation was determined. The effect of spatial location and the requirement of initiator mass, especially at farther locations where the fuel concentration is likely to be lower and closer to the lower explosive limit, was also investigated. The experimental findings help identify the detonable zone in unconfined propylene oxide aerosol clouds for different combinations of spatial location and mass of initiator.

  8. Pressure and Thrust Measurements of a High-Frequency Pulsed Detonation Tube

    NASA Technical Reports Server (NTRS)

    Nguyen, N.; Cutler, A. D.

    2008-01-01

    This paper describes measurements of a small-scale, high-frequency pulsed detonation tube. The device utilized a mixture of H2 fuel and air, which was injected into the device at frequencies of up to 1200 Hz. Pulsed detonations were demonstrated in an 8-inch long combustion volume, at about 600 Hz, for the quarter wave mode of resonance. The primary objective of this experiment was to measure the generated thrust. A mean value of thrust was measured up to 6.0 lb, corresponding to H2 flow based specific impulse of 2970 s. This value is comparable to measurements in H2-fueled pulsed detonation engines (PDEs). The injection and detonation frequency for this new experimental case was much higher than typical PDEs, where frequencies are usually less than 100 Hz. The compact size of the device and high frequency of detonation yields a thrust-per-unit-volume of approximately 2.0 pounds per cubic inch, and compares favorably with other experiments, which typically have thrust-per-unit-volume of order 0.01 pound per cubic inch. This much higher volumetric efficiency results in a potentially much more practical device than the typical PDE, for a wide range of potential applications, including high-speed boundary layer separation control, for example in hypersonic engine inlets, and propulsion for small aircraft and missiles.

  9. Propagation of detonations in hydrazine vapor

    NASA Technical Reports Server (NTRS)

    Heinrich, H. J.

    1985-01-01

    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.

  10. Parametric study of double cellular detonation structure

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  11. SLAG CHARACTERIZATION AND REMOVAL USING PULSE DETONATION TECHNOLOGY DURING COAL GASIFICATION

    SciTech Connect

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

    1998-07-30

    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

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

    PubMed

    Gao, Yang; Law, Chung K

    2011-10-21

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

  13. Estimating heat production in the detonation of poured-density ammonium perchlorate

    SciTech Connect

    Martynyuk, V.F.; Khasainov, B.A.; Sulimov, A.A.; Sukoyan, M.K.

    1987-07-01

    The authors use an electromagnetic method to measure the mass-velocity profile in the detonation of a tamped charge of ammonium perchlorate (APC) in a strong shell. The profile for the mass velocity in the detonation wave was recorded by a two-arm electro-magnetic sensor. Calculations on the two-phase medium together with the mass-velocity profile are shown. High porosity at the front is found; much of the material burns at the front, during the first 0.5 ..mu..sec, which agrees with previous data. It is shown that the porosity in shock compression by a wave of amplitude 10 GPa would be not less than 0.2-0.45, which conflicts with the traditional mass velocity for complete pore collapse in strong shock waves.

  14. Initiation and Detonation Physics on Millimeter Scales

    SciTech Connect

    Philllips, D F; Benterou, J J; May, C A

    2012-03-20

    The LLNL Detonation Science Project has a major interest in understanding the physics of detonation on a millimeter scale. This report summarizes the rate stick experiment results of two high explosives. The GO/NO-GO threshold between varying diameters of ultra-fine TATB (ufTATB) and LX-16 were recorded on an electronic streak camera and analyzed. This report summarizes the failure diameters of rate sticks for ufTATB and LX-16. Failure diameter for the ufTATB explosive, with densities at 1.80 g/cc, begin at 2.34 mm (not maintaining detonation velocity over the entire length of the rate stick). ufTATB rate sticks at the larger 3.18 mm diameter maintain a constant detonation velocity over the complete length. The PETN based and LLNL developed explosive, LX-16, with densities at 1.7 g/cc, shows detonation failure between 0.318 mm and 0.365 mm. Additional tests would be required to narrow this failure diameter further. Many of the tested rate sticks were machined using a femtosecond laser focused into a firing tank - in case of accidental detonation.

  15. Supporting Structure of the LSD Wave in an Energy Absorption Perspective

    SciTech Connect

    Fukui, Akihiro; Hatai, Keigo; Cho, Shinatora; Arakawa, Yoshihiro; Komurasaki, Kimiya

    2008-04-28

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

  16. One Year Term Review as a Participating Guest in the Detonator and Detonation Physics Group

    SciTech Connect

    Lefrancois, A; Roeske, F; Tran, T; Lee, R S

    2006-02-06

    The one year stay was possible after a long administrative process, because of the fact that this was the first participating guest of B division as a foreign national in HEAF (High Explosives Application Facility) with the Detonator/Detonation Physics Group.

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

    NASA Technical Reports Server (NTRS)

    Yungster, S.; Radhakrishnan, K.

    2002-01-01

    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.

  18. Study on the Mechanism of the Deflagration to Detonation Transition Process of Explosive

    NASA Astrophysics Data System (ADS)

    Ying, Yangjun; Hu, Xiaomian; Wei, Lan

    2014-03-01

    In this paper we presented a numerical study of the mechanisms of the deflagration to detonation transition (DDT) process of explosives to assess its thermal stability. We treated the modeling system as a mixture of solid explosives and gaseous reaction products. We utilized a one-dimensional two-phase flow modeling approach with space-time conservation element and solution element (CE/SE) method. Simulation results show a plug area of high density with relatively slow chemical reactions, whose forward boundary is the fast running shock wave, and rearward boundary is the burning wave.We identified a criterion of steady detonation through a detailed analysis of the characteristics of the reaction process: steady detonation occurs at locations where different physical quantities, such as pressure, density, temperature and velocity, reach peak values simultaneously.We also simulated the high temperature DDT tube experiments of HMX-based high explosive. We found good agreement between the simulation results of detonation velocity and run length determined by the above criterion and the experimental results.

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

    PubMed

    Starikovskiy, Andrey; Aleksandrov, Nickolay; Rakitin, Aleksandr

    2012-02-13

    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.

  20. Preliminary Studies of a Pulsed Detonation Rocket Engine

    NASA Technical Reports Server (NTRS)

    Cambier, Jean-Luc; Adelman, H. G.; Menees, G. P.; Edwards, Thomas A. (Technical Monitor)

    1995-01-01

    In the new era of space exploration, there is a strong need for more efficient, cheaper and more reliable propulsion devices. With dramatic increase in specific impulse, the overall mass of fuel to be lifted into orbit is decreased, and this leads, in turn, to much lower mass requirements at lift-off, higher payload ratios and lower launch costs. The Pulsed Detonation engine (PDE) has received much attention lately due to its unique combination of simplicity, light-weight and efficiency. Current investigations focus principally on its use as a low speed, airbreathing engine, although other applications have also been proposed. Its use as a rocket propulsion device was first proposed in 1988 by the present authors. The superior efficiency of the Pulsed Detonation Rocket Engine (PDRE) is due to the near constant volume combustion process of a detonation wave. Our preliminary estimates suggest that the PDRE is theoretically capable of achieving specific impulses as high as 720 sec, a dramatic improvement over the current 480 sec of conventional rocket engines, making it competitive with nuclear thermal rockets. In addition to this remarkable efficiency, the PDRE may eliminate the need for high pressure cryogenic turbopumps, a principal source of failures. The heat transfer rates are also much lower, eliminating the need for nozzle cooling. Overall, the engine is more reliable and has a much lower weight. This paper will describe in detail the operation of the PDRE and calculate its performance, through numerical simulations. Engineering issues will be addressed and discussed, and the impact on mission profiles will also be presented. Finally, the performance of the PDRE using in-situ resources, such as CO and O2 from the martian atmosphere, will also be computed.

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

    PubMed

    Starikovskiy, Andrey; Aleksandrov, Nickolay; Rakitin, Aleksandr

    2012-02-13

    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

  2. Gaseous detonation synthesis and characterization of nano-oxide

    NASA Astrophysics Data System (ADS)

    Yan, Honghao; Wu, Linsong; Li, Xiaojie; Wang, Xiaohong

    2015-07-01

    Gaseous detonation is a new method of heating the precursor of nanomaterials into gas, and integrating it with combustible gas as mixture to be detonated for the synthesis of nanomaterials. In this paper, the mixed gas of oxygen and hydrogen is used as the source for detonation, to synthesize nano TiO2, nano SiO2 and nano SnO2 through gaseous detonation method, characterization and analysis of the products, it was found that the products from gaseous detonation method were of high purity, good dispersion, smaller particle size and even distribution. It also shows that for the synthesis of nano-oxides, gaseous detonation is universal.

  3. Detonability of H/sub 2/-air-diluent mixtures

    SciTech Connect

    Tieszen, S.R.; Sherman, M.P.; Benedick, W.B.; Berman, M.

    1987-06-01

    This report describes the Heated Detonation Tube (HDT). Detonation cell width and velocity results are presented for H/sub 2/-air mixtures, undiluted and diluted with CO/sub 2/ and H/sub 2/O for a range of H/sub 2/ concentration, initial temperature and pressure. The results show that the addition of either CO/sub 2/ or H/sub 2/O significantly increases the detonation cell width and hence reduces the detonability of the mixture. The results also show that the detonation cell width is reduced (detonability is increased) for increased initial temperature and/or pressure.

  4. Detonation nanodiamonds for doping Kevlar.

    PubMed

    Comet, Marc; Pichot, Vincent; Siegert, Benny; Britz, Fabienne; Spitzer, Denis

    2010-07-01

    This paper reports on the first attempt to enclose diamond nanoparticles--produced by detonation--into a Kevlar matrix. A nanocomposite material (40 wt% diamond) was prepared by precipitation from an acidic solution of Kevlar containing dispersed nanodiamonds. In this material, the diamond nanoparticles (Ø = 4 nm) are entirely wrapped in a Kevlar layer about 1 nm thick. In order to understand the interactions between the nanodiamond surface and the polymer, the oxygenated surface functional groups of nanodiamond were identified and titrated by Boehm's method which revealed the exclusive presence of carboxyl groups (0.85 sites per nm2). The hydrogen interactions between these groups and the amide groups of Kevlar destroy the "rod-like" structure and the classical three-dimensional organization of this polymer. The distortion of Kevlar macromolecules allows the wrapping of nanodiamonds and leads to submicrometric assemblies, giving a cauliflower structure reminding a fractal object. Due to this structure, the macroscopic hardness of Kevlar doped by nanodiamonds (1.03 GPa) is smaller than the one of pure Kevlar (2.31 GPa). To our knowledge, this result is the first illustration of the change of the mechanical properties induced by doping the Kevlar with nanoparticles.

  5. Visualization of deflagration-to-detonation transitions in a channel with repeated obstacles using a hydrogen-oxygen mixture

    NASA Astrophysics Data System (ADS)

    Maeda, S.; Minami, S.; Okamoto, D.; Obara, T.

    2016-09-01

    The deflagration-to-detonation transition in a 100 mm square cross-section channel was investigated for a highly reactive stoichiometric hydrogen oxygen mixture at 70 kPa. Obstacles of 5 mm width and 5, 10, and 15 mm heights were equally spaced 60 mm apart at the bottom of the channel. The phenomenon was investigated primarily by time-resolved schlieren visualization from two orthogonal directions using a high-speed video camera. The detonation transition occurred over a remarkably short distance within only three or four repeated obstacles. The global flame speed just before the detonation transition was well below the sound speed of the combustion products and did not reach the sound speed of the initial unreacted gas for tests with an obstacle height of 5 and 10 mm. These results indicate that a detonation transition does not always require global flame acceleration beyond the speed of sound for highly reactive combustible mixtures. A possible mechanism for this detonation initiation was the mixing of the unreacted and reacted gas in the vicinity of the flame front convoluted by the vortex present behind each obstacle, and the formation of a hot spot by the shock wave. The final onset of the detonation originated from the unreacted gas pocket, which was surrounded by the obstacle downstream face and the channel wall.

  6. On the quasi-one dimensional structure of the cellular detonation in a two-dimensional duct

    NASA Astrophysics Data System (ADS)

    Uyeda, C. M.; Kurosaka, M.; Ferrante, A.

    2015-11-01

    We performed numerical simulations of cellular detonations in a 2D duct to establish the validity of the one-dimensional ZND model. The detonation was simulated by solving the Euler equations with a WENO-TCD numerical method using adaptive mesh refinement and a detailed chemical reaction mechanism. The results show that the properties of the ZND model of a 2H2-O2-7Ar reaction are very close to the results of the simulations initiated using three different methods for the area-averaged properties and the properties of particles tracked along their pathlines. Disagreements between the particle properties and the ZND model are greatest near the detonation front where the transverse wave and Mach stem introduce larger jumps in the flow properties than the ZND model predicts. The particle pathlines also exhibit a quasi one-dimensional motion downstream from the detonation front which is supported by the quick decay in the particles' velocity ratio of the vertical to horizontal velocity components, in the reference frame attached to the detonation front. These findings show the quasi one-dimensional nature of 2D detonations and the applicability of the ZND model.

  7. Visualization of deflagration-to-detonation transitions in a channel with repeated obstacles using a hydrogen-oxygen mixture

    NASA Astrophysics Data System (ADS)

    Maeda, S.; Minami, S.; Okamoto, D.; Obara, T.

    2016-05-01

    The deflagration-to-detonation transition in a 100 mm square cross-section channel was investigated for a highly reactive stoichiometric hydrogen oxygen mixture at 70 kPa. Obstacles of 5 mm width and 5, 10, and 15 mm heights were equally spaced 60 mm apart at the bottom of the channel. The phenomenon was investigated primarily by time-resolved schlieren visualization from two orthogonal directions using a high-speed video camera. The detonation transition occurred over a remarkably short distance within only three or four repeated obstacles. The global flame speed just before the detonation transition was well below the sound speed of the combustion products and did not reach the sound speed of the initial unreacted gas for tests with an obstacle height of 5 and 10 mm. These results indicate that a detonation transition does not always require global flame acceleration beyond the speed of sound for highly reactive combustible mixtures. A possible mechanism for this detonation initiation was the mixing of the unreacted and reacted gas in the vicinity of the flame front convoluted by the vortex present behind each obstacle, and the formation of a hot spot by the shock wave. The final onset of the detonation originated from the unreacted gas pocket, which was surrounded by the obstacle downstream face and the channel wall.

  8. Significance of blast wave studies to propulsion.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.

    1971-01-01

    Brief survey of experimental methods currently used for the study of blast wave phenomena with emphasis on high rate exothermic processes. The experimental techniques have used such devices as divergent test sections in shock or detonation tubes, employment of proper test gases, as in marginal detonations, and a variety of explosion systems from finite source explosion apparatus to devices where virtually point explosions are obtained by local breakdown initiated by means of focused laser irradiation. Other methods used are detonation tubes where pressure waves are generated by accelerating flames or by exothermic reactions developed behind reflected shocks, as well as a variety of converging shock and implosion vessels.

  9. Detonation-product behavior at large expansion: the underwater detonation of nitromethane. [KOEOP code

    SciTech Connect

    Helm, F.H. Jr.; Chambers, E.S.; Lee, E.; Finger, M.; McGuire, R.R.; Mahler, J.P.; Cheung, H.; Cramer, J.L.

    1980-12-01

    The expanding product gases of the explosive used in rock fracturing, cratering, and air or underwater explosions do work on the surroundings even at relatively low pressures. To characterize explosives for these applications it is necessary to obtain an almost complete expansion history. An underwater test which was used to measure the shock-wave travel and gas bubble resulting from the detonation of 2 kg of nitromethane is described. The bubble expansion was photographically measured to a volume of about 80 times the initial volume of the shell. These experimental measurements compared well with those calculated by a one-dimensional hydrodynamic program, KOELAS. KOELAS also provided data to assist in the calculation of the apparent position of the shell containing the explosive, using refractive index gradients and the bubble position as a function of time. A method for estimating optical ray paths penetrating the expanding shock front and a modification to a streaking camera that permits stable operation at low rotor speeds are described. The expansion exhibited a minimum pressure of 2 MPa (20 bars), an amount in the range of rock blasting applications, underwater explosions, and rock fracturing or cratering.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Chongyu; Hu, Haibo; Li, Qingzhong; Zhang, Zhengtao; Sun, Xuelin; LaboratoryShock Waves; Detonation Physics Research Team

    2011-06-01

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

  11. GPU-based simulation of the two-dimensional unstable structure of gaseous oblique detonations

    SciTech Connect

    Teng, H.H.; Kiyanda, C.B.; Ng, H.D.; Morgan, G.H.; Nikiforakis, N.

    2015-03-10

    In this paper, the two-dimensional structure of unstable oblique detonations induced by the wedge from a supersonic combustible gas flow is simulated using the reactive Euler equations with a one-step Arrhenius chemistry model. A wide range of activation energy of the combustible mixture is considered. Computations are performed on the Graphical Processing Unit (GPU) to reduce the simulation runtimes. A large computational domain covered by a uniform mesh with high grid resolution is used to properly capture the development of instabilities and the formation of different transverse wave structures. After the initiation point, where the oblique shock transits into a detonation, an instability begins to manifest and in all cases, the left-running transverse waves first appear, followed by the subsequent emergence of right-running transverse waves forming the dual-head triple point structure. This study shows that for low activation energies, a long computational length must be carefully considered to reveal the unstable surface due to the slow growth rate of the instability. For high activation energies, the flow behind the unstable oblique detonation features the formation of unburnt gas pockets and strong vortex-pressure wave interaction resulting in a chaotic-like vortical structure.

  12. Turbulent Mixing and Afterburn in Post-Detonation Flow with Dense Particle Clouds

    NASA Astrophysics Data System (ADS)

    Menon, Suresh

    2015-06-01

    Reactive metal particles are used as additives in most explosives to enhance afterburn and augment the impact of the explosive. The afterburn is highly dependent on the particle dispersal and mixing in the post-detonation flow. The post-detonation flow is generally characterized by hydrodynamic instabilities emanating from the interaction of the blast waves with the detonation product gases and the ambient air. Further, influenced by the particles, the flow evolves and develops turbulent structures, which play vital role in determining mixing and combustion. Past studies in the field in open literature are reviewed along with some recent studies conducted using three dimensional numerical simulations of particle dispersal and combustion in the post-detonation flow. Spherical nitromethane charges enveloped by particle shells of varying thickness are considered along with dense loading effects. In dense flows, the particles block the flow of the gases and therefore, the role of the inter-particle interactions on particle dispersal cannot be ignored. Thus, both dense and dilute effects must be modeled simultaneously to simulate the post-detonation flow. A hybrid equation of state is employed to study the evolution of flow from detonation initiation till the late time mixing and afterburn. The particle dispersal pattern in each case is compared with the available experimental results. The burn rate and the energy release in each case is quantified and the effect of total mass of the particles and the particle size is analyzed in detail. Strengths and limitations of the various methods used for such studies as well as the uncertainties in the modeling strategies are also highlighted. Supported by Defense Threat Reduction Agency.

  13. APPLICATION OF THE EMBEDDED FIBER OPTIC PROBE IN HIGH EXPLOSIVE DETONATION STUDIES: PBX-9502 AND LX-17

    SciTech Connect

    Hare, D; Goosman, D; Lorenz, K; Lee, E

    2006-09-26

    The Embedded Fiber Optic probe directly measures detonation speed continuously in time, without the need to numerically differentiate data, and is a new tool for measuring time-dependent as well as steady detonation speed to high accuracy. It consists of a custom-design optical fiber probe embedded in high explosive. The explosive is detonated and a refractive index discontinuity is produced in the probe at the location of the detonation front by the compression of the detonation. Because this index-jump tracks the detonation front a measurement of the Doppler shift of laser light reflected from the jump makes it possible to continuously measure detonation velocity with high spatial and temporal resolution. We have employed this probe with a Fabry-Perot-type laser Doppler velocimetry system additionally equipped with a special filter for reducing the level of non-Doppler shifted light relative to the signal. This is necessary because the index-jump signal is relatively weak compared to the return expected from a well-prepared surface in the more traditional and familiar example of material interface velocimetry. Our observations were carried out on a number of explosives but this work is focused on our results on PBX-9502 (95% TATB, 5% Kel-F) and LX-17 (92.5% TATB, 7.5% Kel-F) at varying initial charge density. Our measurements reveal a density dependence significantly lower than previous quoted values and lower than theoretical calculations. Our limited data on detonation speed dependence on wave curvature is in reasonable agreement with previous work using more standard methods and confirms deviation from the Wood-Kirkwood theoretical formula.

  14. Structure and properties of detonation soot particles

    SciTech Connect

    MalKOV, I.Y.; Titiov, V.M.

    1996-05-01

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

  15. Convection of a pattern of vorticity through a reacting shock wave

    NASA Technical Reports Server (NTRS)

    Jackson, T. L.; Kapila, A. K.; Hussaini, M. Y.

    1989-01-01

    The passage of a weak vorticity disturbance through a reactive shock wave, or detonation, is examined by means of a linearized treatment. Of special interest is the effect of chemical heat release on the amplification of vorticity in particular, and on the disturbance pattern generated downstream of the detonation in general. It is found that the effect of exothermicity is to amplify the refracted waves. The manner in which the imposed disturbance alters the structure of the detonation itself is also discussed.

  16. Thrust Augmentation Measurements for a Pulse Detonation Engine Driven Ejector

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  17. Diameter Effect Curve and Detonation Front Curvature Measurements for ANFO

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  18. Reduced yield detonation characteristics in large failure diameter materials

    SciTech Connect

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

    1998-08-10

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

  19. Theoretical and computer models of detonation in solid explosives

    SciTech Connect

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

    1997-10-01

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

  20. Finite element code development for modeling detonation of HMX composites

    NASA Astrophysics Data System (ADS)

    Duran, Adam; Sundararaghavan, Veera

    2015-06-01

    In this talk, we present a hydrodynamics code for modeling shock and detonation waves in HMX. A stable efficient solution strategy based on a Taylor-Galerkin finite element (FE) discretization was developed to solve the reactive Euler equations. In our code, well calibrated equations of state for the solid unreacted material and gaseous reaction products have been implemented, along with a chemical reaction scheme and a mixing rule to define the properties of partially reacted states. A linear Gruneisen equation of state was employed for the unreacted HMX calibrated from experiments. The JWL form was used to model the EOS of gaseous reaction products. It is assumed that the unreacted explosive and reaction products are in both pressure and temperature equilibrium. The overall specific volume and internal energy was computed using the rule of mixtures. Arrhenius kinetics scheme was integrated to model the chemical reactions. A locally controlled dissipation was introduced that induces a non-oscillatory stabilized scheme for the shock front. The FE model was validated using analytical solutions for sod shock and ZND strong detonation models and then used to perform 2D and 3D shock simulations. We will present benchmark problems for geometries in which a single HMX crystal is subjected to a shock condition. Our current progress towards developing microstructural models of HMX/binder composite will also be discussed.

  1. Effects of Fuel Distribution on Detonation Tube Performance

    NASA Technical Reports Server (NTRS)

    Perkins, H. Douglas; Sung, Chih-Jen

    2003-01-01

    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.

  2. Differential piston and valving system for detonation device

    SciTech Connect

    Adams, J.S.

    1988-07-26

    A method of producing repeated detonations in a detonation chamber is described comprising: a. arranging a movable differential piston in a differential cylinder around a fixed wall of the detonation chamber so as to form a fluid flow passageway between the detonation chamber wall and the piston; and b. arranging valves to cooperate with the differential piston so that a power stroke of the differential piston draws cooling and purging air into contact with the detonation chamber wall and compresses recharging air and so that a return stroke of the differential piston forces the cooling and purging air through the passageway into the detonation chamber to purge exhaust gas from the detonation chamber and subsequently admits compressed recharging air through the passageway and into the detonation chamber.

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

    SciTech Connect

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

    1994-03-01

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

  4. Quantic Industries Inc. slapper detonator performance

    SciTech Connect

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

    1994-05-01

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

  5. Detonation Properties of Ammonium Dinitramide (ADN)

    NASA Astrophysics Data System (ADS)

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

    1999-06-01

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

  6. Eigenvalue Detonation of Combined Effects Aluminized Explosives

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

  7. Multistage reaction pathways in detonating high explosives

    SciTech Connect

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Nomura, Ken-ichi; Vashishta, Priya

    2014-11-17

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N{sub 2} and H{sub 2}O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N{sub 2} and H{sub 2}O productions.

  8. Detonation Performance Testing of LX-19

    NASA Astrophysics Data System (ADS)

    Vincent, Samuel; Aslam, Tariq; Jackson, Scott

    2015-06-01

    CL-20 was developed at the Naval Surface Weapons Center at China Lake, CA in the mid 80's. Being less sensitive than PETN, but considerably more powerful than HMX, it is the highest energy and density compound known among organic chemicals. LX-19 was developed at LLNL in the early 90's. It is a high-energy plastic bonded explosive, composed of 95.8 wt% CL-20 and 4.2 wt% Estane binder, and is similar to LX-14 (composed of HMX and Estane), but with greater sensitivity characteristics with use of the more energetic CL-20 explosive. We report detonation performance results for unconfined cylindrical rate sticks of LX-19. The experimental diameter effects are shown, along with detonation front shapes, and reaction zone profiles for different test diameters. This data is critical for calibration to Detonation Shock Dynamics (DSD). LA-UR-15-20672.

  9. Some observations on the initiation and onset of detonation.

    PubMed

    Thomas, Geraint

    2012-02-13

    The results of experimental studies during which transition to detonation events occurred are presented. These observations and their interpretation are then discussed, and the conditions for the onset of detonation are described, with particular attention paid to the nature of the phenomena of deflagration-to-detonation transition. The resulting implications for predicting detonation evolution using computational fluid dynamic methods in practical applications are also discussed. PMID:22213666

  10. Some observations on the initiation and onset of detonation.

    PubMed

    Thomas, Geraint

    2012-02-13

    The results of experimental studies during which transition to detonation events occurred are presented. These observations and their interpretation are then discussed, and the conditions for the onset of detonation are described, with particular attention paid to the nature of the phenomena of deflagration-to-detonation transition. The resulting implications for predicting detonation evolution using computational fluid dynamic methods in practical applications are also discussed.

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

    NASA Technical Reports Server (NTRS)

    Oguz, Sirri

    2010-01-01

    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.

  12. A new mechanism for deflagration-to-detonation in porous granular explosives

    NASA Astrophysics Data System (ADS)

    Gifford, M. J.; Luebcke, P. E.; Field, J. E.

    1999-08-01

    An investigation has been carried out into the differences between the deflagration-to-detonation (DDT) process as it occurs in low density [˜30% theoretical maximum density (TMD)] columns of conventional grain size (˜180 μm) pentaerythritol tetranitrate (PETN) and in ultrafine PETN with a grain size ˜1 μm. The principle technique for observing the process utilized charges confined within a steel housing fitted with a polycarbonate slit window. This allowed direct recording of the transition using high speed streak photography. The explosive was thermally ignited using a pyrotechnic mixture with low gaseous emission to minimize any prepressurization of the charge. In addition to the photographic records of the events, the outputs of photodiodes along the length of the column were monitored in order to determine the rate at which the reaction proceeds. The results obtained show that the DDT process in the larger grain PETN at low density was similar in structure to the DDT process at higher densities. In contrast a different mechanism leads to detonation in columns composed of the smaller grain size PETN when packed to densities less than 50% TMD. After ignition hot gases propagate along the column both compacting and igniting material as they pass. After the gases have reached the downstream end of the column, the column continues to burn and the pressure and temperature increase. Some time later initiation takes place at a point along the burning column, and detonation waves propagate in both directions from this point. The detonation waves propagate from the initiation point at speeds that would normally be associated with material compacted to around 60% TMD. The process appears to be in effect a deflagration-to-localized thermal explosion detonation transition.

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

  14. 30 CFR 75.1311 - Transporting explosives and detonators.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Transporting explosives and detonators. 75.1311... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When explosives and detonators are to be transported...

  15. 30 CFR 75.1311 - Transporting explosives and detonators.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Transporting explosives and detonators. 75.1311... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When explosives and detonators are to be transported...

  16. 30 CFR 75.1311 - Transporting explosives and detonators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Transporting explosives and detonators. 75.1311... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When explosives and detonators are to be transported...

  17. 30 CFR 75.1311 - Transporting explosives and detonators.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Transporting explosives and detonators. 75.1311... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When explosives and detonators are to be transported...

  18. 30 CFR 75.1311 - Transporting explosives and detonators.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Transporting explosives and detonators. 75.1311... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1311 Transporting explosives and detonators. (a) When explosives and detonators are to be transported...

  19. 30 CFR 56.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electric Blasting § 56.6400 Compatibility of electric detonators. All electric detonators to be fired in...

  20. 30 CFR 56.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electric Blasting § 56.6400 Compatibility of electric detonators. All electric detonators to be fired in...

  1. 30 CFR 56.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Deenergized circuits near detonators. 56.6402... Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized. Such circuits need not...

  2. 30 CFR 57.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Deenergized circuits near detonators. 57.6402... Electric Blasting-Surface and Underground § 57.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized....

  3. 30 CFR 57.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Compatibility of electric detonators. 57.6400... Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar...

  4. 30 CFR 57.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Compatibility of electric detonators. 57.6400... Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar...

  5. 30 CFR 57.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Deenergized circuits near detonators. 57.6402... Electric Blasting-Surface and Underground § 57.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized....

  6. 30 CFR 56.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Compatibility of electric detonators. 56.6400 Section 56.6400 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electric Blasting § 56.6400 Compatibility of electric detonators. All electric detonators to be fired in...

  7. 30 CFR 56.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Deenergized circuits near detonators. 56.6402... Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized. Such circuits need not...

  8. 30 CFR 57.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compatibility of electric detonators. 57.6400... Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar...

  9. 30 CFR 57.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Deenergized circuits near detonators. 57.6402... Electric Blasting-Surface and Underground § 57.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized....

  10. 30 CFR 57.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Deenergized circuits near detonators. 57.6402... Electric Blasting-Surface and Underground § 57.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized....

  11. 30 CFR 56.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Deenergized circuits near detonators. 56.6402... Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized. Such circuits need not...

  12. 30 CFR 56.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Deenergized circuits near detonators. 56.6402... Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized. Such circuits need not...

  13. 30 CFR 56.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Deenergized circuits near detonators. 56.6402... Electric Blasting § 56.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized. Such circuits need not...

  14. 30 CFR 57.6402 - Deenergized circuits near detonators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Deenergized circuits near detonators. 57.6402... Electric Blasting-Surface and Underground § 57.6402 Deenergized circuits near detonators. Electrical distribution circuits within 50 feet of electric detonators at the blast site shall be deenergized....

  15. 30 CFR 56.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Compatibility of electric detonators. 56.6400... Electric Blasting § 56.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar electrical firing characteristics....

  16. 30 CFR 56.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compatibility of electric detonators. 56.6400... Electric Blasting § 56.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar electrical firing characteristics....

  17. 30 CFR 57.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Compatibility of electric detonators. 57.6400... Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar...

  18. 30 CFR 57.6400 - Compatibility of electric detonators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compatibility of electric detonators. 57.6400... Electric Blasting-Surface and Underground § 57.6400 Compatibility of electric detonators. All electric detonators to be fired in a round shall be from the same manufacturer and shall have similar...

  19. 33 CFR 154.820 - Fire, explosion, and detonation protection.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...: (1) Have a detonation arrester located not more than 6 meters (19.7 ft.) from the facility vapor... detonation arrester located not more than 6 meters (19.7 ft.) from the facility vapor connection; or (2) Have...) Have a detonation arrester located not more than 6 meters (19.7 ft.) from the facility vapor...

  20. LATERALLY PROPAGATING DETONATIONS IN THIN HELIUM LAYERS ON ACCRETING WHITE DWARFS

    SciTech Connect

    Townsley, Dean M.; Moore, Kevin; Bildsten, Lars

    2012-08-10

    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

  1. Computer modeling of electrical performance of detonators

    SciTech Connect

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

    1995-05-01

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

  2. Statistical Hot Spot Model for Explosive Detonation

    SciTech Connect

    Nichols III, A L

    2004-05-10

    The Non-local Thermodynamic Equilibrium Statistical Hot Spot Model (NLTE SHS), a new model for explosive detonation, is described. In this model, the formation, ignition, propagation, and extinction of hot spots is explicitly modeled. The equation of state of the explosive mixture is treated with a nonlocal equilibrium thermodynamic assumption. A methodology for developing the parameters for the model is discussed, and applied to the detonation velocity diameter effect. Examination of these results indicates where future improvements to the model can be made.

  3. Statistical Hot Spot Model for Explosive Detonation

    SciTech Connect

    Nichols, III, A L

    2005-07-14

    The Non-local Thermodynamic Equilibrium Statistical Hot Spot Model (NLTE SHS), a new model for explosive detonation, is described. In this model, the formation, ignition, propagation, and extinction of hot spots is explicitly modeled. The equation of state of the explosive mixture is treated with a non-local equilibrium thermodynamic assumption. A methodology for developing the parameters for the model is discussed, and applied to the detonation velocity diameter effect. Examination of these results indicates where future improvements to the model can be made.

  4. Modeling Initiation in Exploding Bridgewire Detonators

    SciTech Connect

    Hrousis, C A

    2005-05-18

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

  5. Critical energy for direct initiation of detonation induced by laser ablation

    NASA Astrophysics Data System (ADS)

    Ishihara, S.; Suzuki, K.; Inoue, H.; Ishii, K.; Kataoka, H.

    2016-09-01

    This study describes experimental work examining the critical energy for direct initiation of detonation by laser ablation in a stoichiometric acetylene-oxygen mixture. The amount of input energy, the target material, and the surface roughness of the target were varied to study their effects on shock wave generation. Aluminum and stainless steel were used as target materials. The propagating shock wave induced by laser ablation was observed using high-speed shadow imaging. The critical energy for direct initiation of detonation was calculated using the strong blast wave theory. The critical input energy for aluminum was found to be lower than that for stainless steel. Because the thermodynamic critical temperature of aluminum is lower than that of stainless steel, aluminum caused a phase explosion more easily than stainless steel, thus resulting in direct initiation of detonation with a lower amount of input energy. The effects of surface roughness on critical input energy and shock wave generation were negligibly small. The critical initiation energy was estimated to be 10.3 ± 0.2 mJ, which is in agreement with the experimental data obtained in previous work. The estimated critical initiation energy was independent of the target material. However, other predictions of the critical initiation energy by using the cell size overestimated this value because of the scatter in cell size data of an unstable cellular structure. Furthermore, interaction between plasma plumes formed by laser ablation and those formed by breakdown near the target surface might have contributed to requiring a lower amount of energy for initiating detonation.

  6. Critical energy for direct initiation of detonation induced by laser ablation

    NASA Astrophysics Data System (ADS)

    Ishihara, S.; Suzuki, K.; Inoue, H.; Ishii, K.; Kataoka, H.

    2016-01-01

    This study describes experimental work examining the critical energy for direct initiation of detonation by laser ablation in a stoichiometric acetylene-oxygen mixture. The amount of input energy, the target material, and the surface roughness of the target were varied to study their effects on shock wave generation. Aluminum and stainless steel were used as target materials. The propagating shock wave induced by laser ablation was observed using high-speed shadow imaging. The critical energy for direct initiation of detonation was calculated using the strong blast wave theory. The critical input energy for aluminum was found to be lower than that for stainless steel. Because the thermodynamic critical temperature of aluminum is lower than that of stainless steel, aluminum caused a phase explosion more easily than stainless steel, thus resulting in direct initiation of detonation with a lower amount of input energy. The effects of surface roughness on critical input energy and shock wave generation were negligibly small. The critical initiation energy was estimated to be 10.3 ± 0.2 mJ, which is in agreement with the experimental data obtained in previous work. The estimated critical initiation energy was independent of the target material. However, other predictions of the critical initiation energy by using the cell size overestimated this value because of the scatter in cell size data of an unstable cellular structure. Furthermore, interaction between plasma plumes formed by laser ablation and those formed by breakdown near the target surface might have contributed to requiring a lower amount of energy for initiating detonation.

  7. Spontaneous transition of turbulent flames to detonations in unconfined media.

    PubMed

    Poludnenko, Alexei Y; Gardiner, Thomas A; Oran, Elaine S

    2011-07-29

    A deflagration-to-detonation transition (DDT) can occur in environments ranging from experimental and industrial systems to astrophysical thermonuclear (type Ia) supernovae explosions. Substantial progress has been made in explaining the nature of DDT in confined systems with walls, internal obstacles, or preexisting shocks. It remains unclear, however, whether DDT can occur in unconfined media. Here we use direct numerical simulations (DNS) to show that for high enough turbulent intensities unconfined, subsonic, premixed, turbulent flames are inherently unstable to DDT. The associated mechanism, based on the nonsteady evolution of flames faster than the Chapman-Jouguet deflagrations, is qualitatively different from the traditionally suggested spontaneous reaction-wave model. Critical turbulent flame speeds, predicted by this mechanism for the onset of DDT, are in agreement with DNS results. PMID:21867073

  8. Deflagration-to-detonation transition in granular HMX

    SciTech Connect

    Campbell, A.W.

    1980-01-01

    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)

  9. Spontaneous transition of turbulent flames to detonations in unconfined media.

    PubMed

    Poludnenko, Alexei Y; Gardiner, Thomas A; Oran, Elaine S

    2011-07-29

    A deflagration-to-detonation transition (DDT) can occur in environments ranging from experimental and industrial systems to astrophysical thermonuclear (type Ia) supernovae explosions. Substantial progress has been made in explaining the nature of DDT in confined systems with walls, internal obstacles, or preexisting shocks. It remains unclear, however, whether DDT can occur in unconfined media. Here we use direct numerical simulations (DNS) to show that for high enough turbulent intensities unconfined, subsonic, premixed, turbulent flames are inherently unstable to DDT. The associated mechanism, based on the nonsteady evolution of flames faster than the Chapman-Jouguet deflagrations, is qualitatively different from the traditionally suggested spontaneous reaction-wave model. Critical turbulent flame speeds, predicted by this mechanism for the onset of DDT, are in agreement with DNS results.

  10. Laser-shocked energetic materials with metal additives: evaluation of detonation performance

    NASA Astrophysics Data System (ADS)

    Gottfried, Jennifer; Bukowski, Eric

    A focused, nanosecond-pulsed laser with sufficient energy to exceed the breakdown threshold of a material generates a laser-induced plasma with high peak temperatures, pressures, and shock velocities. Depending on the laser parameters and material properties, nanograms to micrograms of material is ablated, atomized, ionized and excited in the laser-induced plasma. The subsequent shock wave expansion into the air above the sample has been monitored using high-speed schlieren imaging in a recently developed technique, laser-induced air shock from energetic materials (LASEM). The estimated detonation velocities using LASEM agree well with published experimental values. A comparison of the measured shock velocities for various energetic materials including RDX, DNTF, and LLM-172 doped with Al or B to the detonation velocities predicted by CHEETAH for inert or active metal participation demonstrates that LASEM has potential for predicting the early time participation of metal additives in detonation events. The LASEM results show that reducing the amount of hydrogen present in B formulations increases the resulting detonation velocities

  11. Mechanisms of deflagration-to-detonation transition under initiation by high-voltage nanosecond discharges

    SciTech Connect

    Rakitin, Aleksandr E.; Starikovskii, Andrei Yu.

    2008-10-15

    An experimental study of detonation initiation in a stoichiometric propane-oxygen mixture by a high-voltage nanosecond gas discharge was performed in a detonation tube with a single-cell discharge chamber. The discharge study performed in this geometry showed that three modes of discharge development were realized under the experimental conditions: a spark mode with high-temperature channel formation, a streamer mode with nonuniform gas excitation, and a transient mode. Under spark and transient initiation, simultaneous ignition inside the discharge channel occurred, forming a shock wave and leading to a conventional deflagration-to-detonation transition (DDT) via an adiabatic explosion. The DDT length and time at 1 bar of initial pressure in the square smooth tube with a 20-mm transverse size amounted to 50 mm and 50{mu}s, respectively. The streamer mode of discharge development at an initial pressure of 1 bar resulted in nonuniform mixture excitation and a successful DDT via a gradient mechanism, which was confirmed by high-speed time resolved ICCD imaging. The gradient mechanism implied a longer DDT time of 150{mu}s, a DDT run-up distance of 50 mm, and an initiation energy of 1 J, which is two orders of magnitude less than the direct initiation energy for a planar detonation under these conditions. (author)

  12. A Multi-Component Model that Describes Weak Detonation in Blast Explosives

    NASA Astrophysics Data System (ADS)

    Stewart, D. Scott; Asay, Blaine; Bdzil, John; Foster, Joseph; Hernández, Alberto; Lambert, David

    2015-06-01

    Recently our group proposed a conceptual, multi-component model of an explosive material that admits weak (sonic) detonation. The weak detonation has the property that its propagation speed and wave structure is a function of the reaction rate of decomposition of reactants to products. The simplest version of the model assumes that a blast explosive has three components, reactants, intermediates and products. For many cases of interest this model is applicable if the first step is an endothermic reaction to intermediates followed by an exothermic reaction to products. Analysis shows that the properties of the weak detonation depend on the ratio of the first and second reaction rates. The decomposition steps, each can be endothermic or exothermic, but the overall reaction must be exothermic. We present both a theoretical and an engineering analysis of a typical explosive in this class and demonstrate by means of accompanying numerical simulations, that a three component reactive flow model that has a fast exothermic step to intermediates, followed by a slower endothermic step to final products produces weak detonation. Supported by FA8651-10-1-0004 (AFRL/RW) and N000014-12-1-0555 (ONR).

  13. Experimental Measurements of the Chemical Reaction Zone of Detonating Liquid Explosives

    NASA Astrophysics Data System (ADS)

    Bouyer, Viviane; Sheffield, Stephen A.; Dattelbaum, Dana M.; Gustavsen, Richard L.; Stahl, David B.; Doucet, Michel; Decaris, Lionel

    2009-12-01

    We have a joint project between CEA-DAM Le Ripault and Los Alamos National Laboratory (LANL) to study the chemical reaction zone in detonating high explosives using several different laser velocimetry techniques. The short temporal duration of the von Neumann spike and early part of the reaction zone make these measurements difficult. Here, we report results obtained from detonation experiments using VISAR (velocity interferometer system for any reflector) and PDV (photon Doppler velocimetry) methods to measure the particle velocity history at a detonating nitromethane/PMMA interface. Experiments done at CEA were high-explosive-plane-wave initiated and those at LANL were gas-gun-projectile initiated with a detonation run of about 6 charge diameters in all experiments. The experiments had either glass or brass confinement. Excellent agreement of the interface particle velocity measurements at both Laboratories were obtained even though the initiation methods and the velocimetry systems were somewhat different. Some differences were observed in the peak particle velocity because of the ˜2 ns time resolution of the techniques—in all cases the peak was lower than the expected von Neumann spike. This is thought to be because the measurements were not high enough time resolution to resolve the spike.

  14. Performance Evaluation of Hybrid Gas Turbine Engine Embedded with Pulse Detonation Combustor

    NASA Astrophysics Data System (ADS)

    Deng, Jun-Xiang; Yan, Chuan-Jun; Zheng, Long-Xi; Huang, Xi-Qiao

    2011-09-01

    The numerical investigations of performance evaluation of a hybrid gas turbine engine embedded with a pulse detonation combustor (PDC) were performed to examine the improvement of the performance of the hybrid propulsion system. The calculation model and method were described. The architecture, configuration and size of detonation tubes were investigated in the calculation. Two models of detonation tube exit temperature were utilized. Eight configuration choices for the PDC based on the calculation model were designed. Specific fuel consumption of a hybrid gas turbine engine was compared with that of the baseline engine at the condition of the same engine net thrust. The experimental research of a PDC interacted with a radial flow turbine of a turbocharger was conducted. The numerical results show that if the net thrust of hybrid PDC engine is matched to that of baseline engine, specific fuel consumption of hybrid PDC engine is 20-25% less than that of baseline engine. The total volume of the hybrid engine combustor is reduced. The incorporation of PDC into gas turbine engine can improve the performance of hybrid PDC engine, decrease the combustor weight, and increase the thrust-weight ratio. The experimental results show that the fully developed detonation waves are achieved in the experimental apparatus.

  15. Measurement and scaling analysis of critical energy for direct initiation of gaseous detonations

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    In this paper, the critical energies required for direct initiation of spherical detonations in four gaseous fuels (C2H2, C2H4, C3H8 and H2)-oxygen mixtures at different initial pressures, equivalence ratios and with different amounts of argon dilution are reported. Using these data, a scaling analysis is performed based on two main parameters of the problem: the explosion length R o that characterizes the blast wave and a characteristic chemical length that characterizes the detonation. For all the undiluted mixtures considered in this study, it is found that the relationship is closely given by {R_o ≈ 26 λ} , where λ is the characteristic detonation cell size of the explosive mixture. While for C2H2-2.5O2 mixtures highly diluted with argon, in which cellular instabilities are shown to play a minor role on the detonation propagation, the proportionality factor increases to 37.3, 47 and 54.8 for 50, 65 and 70% argon dilution, respectively. Using the ZND induction length Δ I as the characteristic chemical length scale for argon diluted or `stable' mixtures, the explosion length is also found to scale adequately with {R_o ≈ 2320 Δ_I}.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  17. Axisymmetric Numerical Modeling of Pulse Detonation Rocket Engines

    NASA Technical Reports Server (NTRS)

    Morris, Christopher I.

    2005-01-01

    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

  18. Attosecond shock waves.

    PubMed

    Zhokhov, P A; Zheltikov, A M

    2013-05-01

    Shock-wave formation is a generic scenario of wave dynamics known in nonlinear acoustics, fluid dynamics, astrophysics, seismology, and detonation physics. Here, we show that, in nonlinear optics, remarkably short, attosecond shock transients can be generated through a strongly coupled spatial and temporal dynamics of ultrashort light pulses, suggesting a pulse self-compression scenario whereby multigigawatt attosecond optical waveforms can be synthesized. PMID:23683197

  19. Close-in Blast Waves from Spherical Charges*

    NASA Astrophysics Data System (ADS)

    Howard, William; Kuhl, Allen

    2011-06-01

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

  20. Hydrogen-oxygen flame acceleration and transition to detonation in channels with no-slip walls for a detailed chemical reaction model.

    PubMed

    Ivanov, M F; Kiverin, A D; Liberman, M A

    2011-05-01

    The features of flame acceleration in channels with wall friction and the deflagration to detonation transition (DDT) are investigated theoretically and using high resolution numerical simulations of two-dimensional reactive Navier-Stokes equations, including the effects of viscosity, thermal conduction, molecular diffusion, and a detailed chemical reaction mechanism for hydrogen-oxygen gaseous mixture. It is shown that in a wide channel, from the beginning, the flame velocity increases exponentially for a short time and then flame acceleration decreases, ending up with the abrupt increase of the combustion wave velocity and the actual transition to detonation. In a thin channel with a width smaller than the critical value, the exponential increase of the flame velocity is not bounded and ends up with the transition to detonation. The transition to detonation occurs due to the pressure pulse, which is formed at the tip of the accelerating flame. The amplitude of the pressure pulse grows exponentially due to a positive feedback coupling between the pressure pulse and the heat released in the reaction. Finally, large amplitude pressure pulse steepens into a strong shock coupled with the reaction zone forming the overdriven detonation. The evolution from a temperature gradient to a detonation via the Zeldovich gradient mechanism and its applicability to the deflagration-to-detonation transition is investigated for combustible materials whose chemistry is governed by chain-branching kinetics. The results of the high resolution simulations are fully consistent with experimental observations of the flame acceleration and DDT. PMID:21728653

  1. Hydrogen-oxygen flame acceleration and transition to detonation in channels with no-slip walls for a detailed chemical reaction model.

    PubMed

    Ivanov, M F; Kiverin, A D; Liberman, M A

    2011-05-01

    The features of flame acceleration in channels with wall friction and the deflagration to detonation transition (DDT) are investigated theoretically and using high resolution numerical simulations of two-dimensional reactive Navier-Stokes equations, including the effects of viscosity, thermal conduction, molecular diffusion, and a detailed chemical reaction mechanism for hydrogen-oxygen gaseous mixture. It is shown that in a wide channel, from the beginning, the flame velocity increases exponentially for a short time and then flame acceleration decreases, ending up with the abrupt increase of the combustion wave velocity and the actual transition to detonation. In a thin channel with a width smaller than the critical value, the exponential increase of the flame velocity is not bounded and ends up with the transition to detonation. The transition to detonation occurs due to the pressure pulse, which is formed at the tip of the accelerating flame. The amplitude of the pressure pulse grows exponentially due to a positive feedback coupling between the pressure pulse and the heat released in the reaction. Finally, large amplitude pressure pulse steepens into a strong shock coupled with the reaction zone forming the overdriven detonation. The evolution from a temperature gradient to a detonation via the Zeldovich gradient mechanism and its applicability to the deflagration-to-detonation transition is investigated for combustible materials whose chemistry is governed by chain-branching kinetics. The results of the high resolution simulations are fully consistent with experimental observations of the flame acceleration and DDT.

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

    SciTech Connect

    Deiterding, Ralf

    2007-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Varosh, Ron

    1994-01-01

    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.

  4. Size effect and detonation front curvature

    SciTech Connect

    Souers, P. C., LLNL

    1997-07-01

    Heat flow in a cylinder with internal heating is used as a basis for deriving a simple theory of detonation front curvature, leading to the prediction of quadratic curve shapes. A thermal conductivity of 50 MW/mm{sup 2} is found for TATB samples.

  5. Screen Secures Detonator to Explosive Charge

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  6. Equation of State for Detonation Product Gases

    NASA Astrophysics Data System (ADS)

    Nagayama, Kunihito; Kubota, Shiro

    2013-06-01

    Based on the empirical linear relationship between detonation velocity and loading density, an approximate description for the Chapman-Jouguet state for detonation product gases of solid phase high explosives has been developed. Provided that the Grüneisen parameter is a function only of volume, systematic and closed system of equations for the Grüneisen parameter and CJ volume have been formulated. These equations were obtained by combining this approximation with the Jones-Stanyukovich-Manson relation together with JWL isentrope for detonation of crystal density PETN. A thermodynamic identity between the Grüneisen parameter and another non-dimensional material parameter introduced by Wu and Jing can be used to derive the enthalpy-pressure-volume equation of state for detonation gases. This Wu-Jing parameter is found to be the ratio of the Grüneisen parameter and the adiabatic index. Behavior of this parameter as a function of pressure was calculated and revealed that their change with pressure is very gradual. By using this equation of state, several isentropes down from the Chapman-Jouguet states reached by four different lower initial density PETN have been calculated and compared with available cylinder expansion tests.

  7. Ethylene-air detonation in water spray

    NASA Astrophysics Data System (ADS)

    Jarsalé, G.; Virot, F.; Chinnayya, A.

    2016-09-01

    Detonation experiments are conducted in a 52 {mm} square channel with an ethylene-air gaseous mixture with dispersed liquid water droplets. The tests were conducted with a fuel-air equivalence ratio ranging from 0.9 to 1.1 at atmospheric pressure. An ultrasonic atomizer generates a polydisperse liquid water spray with droplet diameters of 8.5-12 μm, yielding an effective density of 100-120 g/m3. Pressure signals from seven transducers and cellular structure are recorded for each test. The detonation structure in the two-phase mixture exhibits a gaseous-like behaviour. The pressure profile in the expansion fan is not affected by the addition of water. A small detonation velocity deficit of up to 5 % was measured. However, the investigation highlights a dramatic increase in the cell size (λ ) associated with the increase in the liquid water mass fraction in the two-phase mixture. The detonation structure evolves from a multi-cell to a half-cell mode. The analysis of the decay of the post-shock pressure fluctuations reveals that the ratio of the hydrodynamic thickness over the cell size (x_{{HT}}/{λ }) remains quite constant, between 5 and 7. A slight decrease of this ratio is observed as the liquid water mass fraction is increased, or the ethylene-air mixture is made leaner.

  8. Ethylene-air detonation in water spray

    NASA Astrophysics Data System (ADS)

    Jarsalé, G.; Virot, F.; Chinnayya, A.

    2016-07-01

    Detonation experiments are conducted in a 52 mm square channel with an ethylene-air gaseous mixture with dispersed liquid water droplets. The tests were conducted with a fuel-air equivalence ratio ranging from 0.9 to 1.1 at atmospheric pressure. An ultrasonic atomizer generates a polydisperse liquid water spray with droplet diameters of 8.5-12 μm, yielding an effective density of 100-120 g/m3 . Pressure signals from seven transducers and cellular structure are recorded for each test. The detonation structure in the two-phase mixture exhibits a gaseous-like behaviour. The pressure profile in the expansion fan is not affected by the addition of water. A small detonation velocity deficit of up to 5 % was measured. However, the investigation highlights a dramatic increase in the cell size (λ ) associated with the increase in the liquid water mass fraction in the two-phase mixture. The detonation structure evolves from a multi-cell to a half-cell mode. The analysis of the decay of the post-shock pressure fluctuations reveals that the ratio of the hydrodynamic thickness over the cell size (x_{{HT}}/{λ } ) remains quite constant, between 5 and 7. A slight decrease of this ratio is observed as the liquid water mass fraction is increased, or the ethylene-air mixture is made leaner.

  9. Amplification of Pressure Waves during Vibrational Equilibration of Excited Chemical Reaction Products

    SciTech Connect

    Tarver, C M

    2004-05-11

    The Non-Equilibrium Zeldovich - von Neumann - Doring (NEZND) theory of self-sustaining detonation identified amplification of pressure wavelets during equilibration of vibrationally excited reaction products in the reaction zone as the physical mechanism by which exothermic chemical energy release sustains detonation waves. This mechanism leads to the formation of the well-known, complex three-dimensional structure of a self-sustaining detonation wave. This amplification mechanism is postulated to be a general property of subsonic and supersonic reactive flows occurring during: shock to detonation transition (SDT); hot spot ignition and growth; deflagration to detonation transition (DDT); flame acceleration by shock or compression waves; and acoustic (sound) wave amplification. The existing experimental and theoretical evidence for pressure wave amplification by chemical energy release into highly vibrationally excited product molecules under these reactive flow conditions is reviewed in this paper.

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

    SciTech Connect

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.; Gerlach, L.; Tagawa, H.; Malliakos, A.

    1995-12-31

    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.

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

    SciTech Connect

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.

    1996-03-01

    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 products, 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.

  12. Anomalous shock initiation of detonation in pentaerythritol tetranitrate crystals

    SciTech Connect

    Dick, J.J.

    1997-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  14. Non-equilibrium Numerical Analysis of Microwave-supported Detonation Threshold Propagating through Diatomic Gas

    NASA Astrophysics Data System (ADS)

    Shiraishi, Hiroyuki

    2015-09-01

    Microwave-supported Detonation (MSD), one type of Microwave-supported Plasma (MSP), is considered as one of the most important phenomena because it can generate high pressure and high temperature for beam-powered space propulsion systems. In this study, I numerically simulate MSD waves propagating through a diatomic gas. In order to evaluate the threshold of beam intensity, I use the physical-fluid dynamics scheme, which has been developed for simulating unsteady and non-equilibrium LSD waves propagating through a hydrogen gas.

  15. PULSATING REVERSE DETONATION MODELS OF TYPE Ia SUPERNOVAE. I. DETONATION IGNITION

    SciTech Connect

    Bravo, Eduardo; GarcIa-Senz, Domingo E-mail: domingo.garcia@upc.edu

    2009-04-20

    Observational evidences point to a common explosion mechanism of Type Ia supernovae based on a delayed detonation of a white dwarf (WD). Although several scenarios have been proposed and explored by means of one, two, and three-dimensional simulations, the key point still is the understanding of the conditions under which a stable detonation can form in a destabilized WD. One of the possibilities that have been invoked is that an inefficient deflagration leads to the pulsation of a Chandrasekhar-mass WD, followed by formation of an accretion shock around a carbon-oxygen rich core. The accretion shock confines the core and transforms kinetic energy from the collapsing halo into thermal energy of the core, until an inward moving detonation is formed. This chain of events has been termed Pulsating Reverse Detonation (PRD). In this work we explore the robustness of the detonation ignition for different PRD models characterized by the amount of mass burned during the deflagration phase, M {sub defl}. The evolution of the WD up to the formation of the accretion shock has been followed with a three-dimensional hydrodynamical code with nuclear reactions turned off. We found that detonation conditions are achieved for a wide range of M {sub defl}. However, if the nuclear energy released during the deflagration phase is close to the WD binding energy ({approx}0.46 x 10{sup 51} erg {yields} M {sub defl} {approx} 0.30 M {sub sun}) the accretion shock cannot heat and confine the core efficiently and detonation conditions are not robustly achieved.

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

    SciTech Connect

    Sheffield, Stephen A; Dattelbaum, Dana M; Stahl, David B; Gibson, L Lee; Bartram, Brian D; Engelke, Ray

    2010-01-01

    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.

  17. Implementation of Smoothed Particle Hydrodynamics for Detonation of Explosive with Application to Rock Fragmentation

    NASA Astrophysics Data System (ADS)

    Pramanik, R.; Deb, D.

    2015-07-01

    The paper presents a methodology in the SPH framework to analyze physical phenomena those occur in detonation process of an explosive. It mainly investigates the dynamic failure mechanism in surrounding brittle rock media under blast-induced stress wave and expansion of high pressure product gases. A program burn model is implemented along with JWL equation of state to simulate the reaction zone in between unreacted explosive and product gas. Numerical examples of detonation of one- and two-dimensional explosive slab have been carried out to investigate the effect of reaction zone in detonation process and outward dispersion of gaseous product. The results are compared with those obtained from existing solutions. A procedure is also developed in SPH framework to apply continuity conditions between gas and rock interface boundaries. The modified Grady-Kipp damage model for the onset of tensile yielding and Drucker-Prager model for shear failure are implemented for elasto-plastic analysis of rock medium. The results show that high compressive stress causes high crack density in the vicinity of blast hole. The major principal stress (tensile) is responsible for forming radial cracks from the blast hole. Spalling zones are also developed due to stress waves reflected from the free surfaces.

  18. Dynamics of the detonation products of lead azide. IV. Laser shadowgraphy of expanding species

    NASA Astrophysics Data System (ADS)

    Tzuk, Y.; Bar, I.; Rosenwaks, S.

    1993-11-01

    Laser resonant shadowgraphy (LRS) and laser nonresonant shadowgraphy (LNRS) are used to monitor the detonation products of lead azide. Photographs of the cloud of products are obtained via illumination with a doubled dye laser tuned on-resonance to the 3P1o-3P0 transition of the Pb atom at 283.31 nm, and off-resonance at 284.31 nm. The versatility of the diagnostics and its applicability to detonation products expanding into vacuum and into atmospheric pressure air are demonstrated. The LRS monitors the density gradients of both lead atoms and solid particles formed in the detonation, whereas the LNRS detects only the latter. Expansion into vacuum through a nozzle leads to an increase in the velocity (from ˜4.5 to ≳5 km/s) and density of the atoms and to a decrease in the density of the particles. The LRS measurements show that the expansion of both products in air is relatively slow (˜0.75 km/s) and leads to production of shock waves. From the shape of the shock waves created by an obstacle when the products expand into vacuum, the Mach number is estimated to be ≳20 in the outer parts and around 3 in the inner parts of the cloud.

  19. Simulation of the Reflected Blast Wave froma C-4 Charge

    SciTech Connect

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

    2011-08-01

    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.

  20. Proton radiography of PBX 9502 detonation shock dynamics confinement sandwich test

    SciTech Connect

    Aslam, Tariq D; Jackson, Scott I; Morris, John S

    2009-01-01

    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.