DETONATOR: EVOLUTION, CLASSIFICATION AND COMPARISON

A simultaneous initiation of an explosive charge from two or more points can generate a localized increase in pressure, and other detonation parameters, in relation to the stable detonation of the used explosive. To achieve this increase in parameters, more or less complex initiation system has to be utilized. This paper presents a simple and inexpensive system for a simultaneous and parallel two-point initiation of an explosive charge. This system consists of a primary explosive -initiator and an attenuator made of polyetilene with two cylindrical channels -initiation points, filled with plastic explosive. The channels were placed at 24 mm distance from each other, but any distance can be used. The experiments confirmed that a simultaneous initiation was achieved.

Shock Waves, 2005

Experiments of direct initiation of hydrogen-oxygen by means of a hot turbulent jet were made. Results indicate that the length of ignition tube is the dominant factor in determining the ignition capability of hot turbulent jet, and that the ignition capability of turbulence jet increases with the length of ignition tube. Because this ignition capability can meet the demands of a gas-detonation-driver shock tunnel and it doesn't require additional facilities, the hot turbulent jet initiation method can be applied to large hydrogen-oxygen detonationdriver shock tunnels. Influences of obstacles on the ignition capability were also studied. It was found that the presence of obstacles weakens the ignition capability of a hot turbulent jet.

Approved for public release; distribution unlimited 17. DISTRIBUTIO N STATEMENT (ol <n. abatrac, entered In Block 20, II dlU.rent Itoo, Report) 18. SUPPLEMENTARY NOTES 19. KEY WOROS (Continue on ,.v.,.. aide II nec.esery end Identity by block number) Detonation Two-phase detonation Direct initiation of self-sustained detonation 20 ABSTRACT rCon.lnu. on ,.,.,.. aide // neceee.ry «nd Identity by block number) An analytical model of the direct initiation of detonation waves with planar cylindrical, and spherical symmetry is developed. This model shows that the enersy requirements for the self-sustained detonation wave differ significantly for planar, cylindrical and spherical detonations The new concept of minimum compensation energy was introduced and the technique or calculation of minimum initiation energy was developed The results are verified by numerical simulation of the ful l governing equations and by comparison to experimental data. pjj.

AIP Conference Proceedings, 2002

The initiation of detonation in a homogenous liquid explosive by the reflection of a strong shock from a high impedance anvil is investigated. By transmitting a sub-critical shock through a test sample of sensitized nitromethane and then reflecting it normally off a steel plate bounding the explosive, detonation can be initiated in the pre-shocked medium. The initiation of detonation is observed via fiber optics monitored by photodiodes and by manganin pressure gauges mounted on the steel plate. The initiation of detonation by the reflected shock is inferred from the appearance of intense luminosity and an increase in pressure at the explosive/steel interface, both appearing about 1 jas after shock reflection. The manganin gauge measurements indicate that the critical pressure for incident initiation by a 100 mm diameter shock is 4-5 GPa, while the critical pressure for reflected shock initiation is 7 GPa.

Scientific Technical Review, 2015

A simultaneous initiation of an explosive charge from two or more points can generate a localized increase in pressure, and other detonation parameters, in relation to the stable detonation of the used explosive. To achieve this increase in parameters, more or less complex initiation system has to be utilized. This paper presents a simple and inexpensive system for a simultaneous and parallel two-point initiation of an explosive charge. This system consists of a primary explosive-initiator and an attenuator made of polyetilene with two cylindrical channels-initiation points, filled with plastic explosive. The channels were placed at 24 mm distance from each other, but any distance can be used. The experiments confirmed that a simultaneous initiation was achieved.

Symposium (International) on …, 1998

Initiation of gaseous detonation in hydrogen, ethylene, and acetylene-air mixtures by a line source of condensed explosives (detonating cord) is investigated experimentally. Initiation in the cylindrical geometry is important in validating a general theory of initiation and has particular significance to the interaction of high-velocity projectiles with combustible gas. The flowfields generated by the detonating cord resemble the flows observed around blunt hypersonic projectiles in combustible gas, with oblique detonation being observed in good agreement with theoretical predictions. When the energy of the detonating cord greatly exceeds the critical energy per unit length to initiate a cylindrical detonation, the blast wave generated by the cord decays monotonically to the Chapman-Jouguet (CJ) detonation speed. As the source energy approaches the critical energy predicted by theoretical models of initiation, the results become increasingly complex. In these cases, the blast wave and combustion front first decay to sub-CJ velocity, then exhibit oscillations before the final onset of detonation. The initiation of gaseous detonation is also no longer sequential along the length of the cord and is instead associated with discrete explosion centers. This phenomenon is similar to what has been previously observed in spherical initiation, suggesting a universal mechanism of detonation initiation.

Doklady Physical Chemistry, 2007

Journal of Fluid Mechanics, 2003

The direct initiation of gaseous detonation is investigated experimentally in the cylindrical geometry. By using a long source of energy deposition along a line (i.e. pentaerythritoltetranitrate (PETN) detonating cord), undesirable charge initiation and confinement effects are eliminated. This permitted the different flow fields of direct initiation of detonation to be studied unambiguously. Although the detonation velocity in the detonating cord is finite, it was sufficiently large compared to the acoustic velocity in the surrounding gas to permit the different flow fields to be investigated within the hypersonic analogy framework, by which the detonating cord synchronizes a continuous series of cylindrical initiation events along its length. The hypersonic approximation was validated in experiments conducted in a non-reactive medium (air). In the supercritical regime of initiation in combustible gas, stable oblique detonations were observed, confirming their existence and stability. In the critical regime, the onset of detonation was observed to occur consistently from stochastic detonative centres. These centres appeared during the initial decay of the blast wave to sub-Chapman-Jouguet (CJ) velocities. The photographic evidence revealed the three-dimensional details of the detonation kernels' amplification. The present results in the cylindrical geometry are further used to discuss criteria for direct initiation of detonations. In conjunction with previous experiments in the spherical and planar geometries, a criterion for direct initiation is found to involve a critical decay rate of the reacting blast wave. In light of the experimental evidence of the inherent three-dimensional effects during the initiation phase, the strict one-dimensionality of current theoretical models is discussed.

Shock Waves, 2005