The performance of a diaphragm shock tube with an imploding detonation driver is theoretically and experimentally investigated. Strong shock waves are produced by a driver in which a detonation is forced to implode to the apex of a conical channel. In this geometry, the area convergence experienced by the imploding front elevates the driver gas temperature and pressure above the usual Chapman-Jouguet values, thereby increasing the strength of the test shock. Theoretically, the relationship between test shock strength, filling pressure, and area reduction in a conical channel is studied. Experimentally, the importance of the geometric parameters - slant angle, channel width and channel convergence - is investigated. The performance of the conical implosion driver compares well with that of other membrane shock tubes. For instance, for oxy-acetylene detonations, driving into argon of 5 Torr, a Mach number greater than 13 may be reached for a driver to test gas pressure ratio of 100. The same Mach number available from a Chapman-Jouguet detonation driver occurs only above a pressure ratio of 200. For cold hydrogen and constant volume oxy-hydrogen combustion, pressure ratios of 10⁶ and 2 X 10⁴ respectively are required to produce Mach 13. Design criteria for a large area reduction driving facility are also given. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

No description available.

Laser detonators offer several advantages over traditional electrical detonators, such as exploding bridgewire and slapper detonators, in terms of both safety and performance. Laser detonators remove the electrical conduction path to the energetic material, providing immunity from threats such as electrostatic discharge and lightning. A larger separation between the initiating energy source and the explosive devices is possible, up to several tens of metres, compared to a few metres for electrical slapper detonators. A laser detonator system has been developed, with laser-driven flyer plates used to shock initiate the explosive. All aspects of the system, including coupling into an optical fibre, used to transmit the laser energy to the detonator, the optical fibre, the flyer plate launch and acceleration and subsquent shock into the explosive, and the explosive initiation have been investigated, with an understanding of the underlying principles and processes developed. Shock initiation of two secondary explosives, hexanitrostilbene and pentaerythritol tetranitrate, has been studied at extremely high shock pressures, comparable to the detonation pressure, and the critical energy fluence required for initiation established. The laser detonator system is robust and optimised, with design tools developed to enable efficient design of future systems.

Thesis (Masters Diploma (Electrical Engineering)--Cape Technikon, Cape Town, 1988 / The subject of this thesis is the development of ahighly ruggedised, reliable electronic circuit. The circuit is to be used for the initiation of fuze heads and to charge a capacitor for later use in apyrotechnic chain. This circuit and its associated packaging will be called the firing unit. The thesis can be broadly divided into the following facets. I. The definition study, which defines what is needed and proposed means of achieving the customer requirements. 11. The design of the electronic circuitry in the system. Ii!. The design of the packaging containing the electronics. Iv. Adaptation of environmental testing, to verify system design. V. Implementation of environmental testing. Vi. Reliability analysis. Vii. Failure analysis and the determination of the effect of the supposed failure. Actions vto vii were used as inputs to improve 11 and ill, so achieving optimum performance and safety. The whole system was designed with the overriding objective of reliability and safety of personnel and equipment.

Laser detonators offer several advantages over traditional electrical detonators, such as exploding bridgewire and slapper detonators, in terms of both safety and performance. Laser detonators remove the electrical conduction path to the energetic material, providing immunity from threats such as electrostatic discharge and lightning. A larger separation between the initiating energy source and the explosive devices is possible, up to several tens of metres, compared to a few metres for electrical slapper detonators. A laser detonator system has been developed, with laser-driven flyer plates used to shock initiate the explosive. All aspects of the system, including coupling into an optical fibre, used to transmit the laser energy to the detonator, the optical fibre, the flyer plate launch and acceleration and subsquent shock into the explosive, and the explosive initiation have been investigated, with an understanding of the underlying principles and processes developed. Shock initiation of two secondary explosives, hexanitrostilbene and pentaerythritol tetranitrate, has been studied at extremely high shock pressures, comparable to the detonation pressure, and the critical energy fluence required for initiation established. The laser detonator system is robust and optimised, with design tools developed to enable efficient design of future system / © Cranfield University, 2014

A major industrial use of pyrotechnic compositions is as delay fuses in electric detonators. Suitable delay times may be achieved through (i) choice of chemical components (ii) adjustment of composition of the system chosen and, finally, (iii) adjustment of the length of fuse used. This study forms part of a survey of binary fuel/oxidant combinations in an attempt to provide some fundamental information on the first step above: (i) choice of chemical components. The complete survey has included studies of a single fuel in combination with one of a variety of oxidants, and studies of the oxidation of one of several different fuels separately by barium peroxide and strontium peroxide. This study is part of this second approach and the fuels chosen were iron and zinc powders, mainly for chemical reasons (including the potential for use of thermomagnetometry on the iron systems), but also for possible environmental advantages. The mixed oxide products of pyrotechnic combustion could also have some scientific and/or commercial value. The techniques used included thermal analyses of mixtures and their individual components, and measurements of temperature-time profiles during combustion. Thermodynamic and kinetic information was obtained under a variety of conditions and scanning electron microscopy and X-ray diffraction and microprobe analyses provided additional information. Possible mechanisms of reactions are discussed in detail. The practical conclusions were that any potential use which the Fe/peroxide systems may have as delay compositions, with burning-rates of from 3-30 mm s⁻¹, is offset by the susceptibility of the oxidants to reaction with water and CO₂ in the atmosphere. The Zn/BaO₂ and Zn/SrO₂ systems did not burn under compaction, and combustion of uncompacted powders was erratic. Zinc liquid (and probably zinc vapour) take part in the reaction and the gaseous nature of the combustion makes zinc-fuelled pyrotechnic systems unsuitable for delay applications. All the techniques used showed the heterogeneity of the solid residues of combustion. If these residues were to be of any value, they would need further conventional treatment involving grinding of the residue, possible adjustment of compositions, and calcining to produce uniform materials.

No description available.

Thesis (M.Sc)(Chemical Technology, Engineering and Technology Management)--University of Pretoria, 2005. / Includes summary. Includes bibliographical references (leaves 75-80).

Thesis (M.Eng.)(Chemical)--University of Pretoria, 2004. / Includes summary. Includes bibliographical references.

M.Sc. / At the very roots of this dissertation lies a commercial process with many as yet unexplored characteristics that will be thoroughly examined, using a rich variety of statistical methods and techniques. Broadly speaking, the main objective of this study involves the development of techniques to control the quality of advanced explosives detonators used in commercial mining operations. To accomplish this task, various statistical characteristics of this detonation process are described and examined in order to obtain a holistic understanding of the underlying process. The parameters of the process are introduced and estimates for unknowns are derived. Real-time quality control techniques based on these results are suggested. 1.2. The role of blasting in mining A major part of South Africa's economy is based on the mining of the rich mineral deposits that are to be found in the country. These mining operations are carried out both above ground (open-pit iron ore mines, for example) and below ground (gold, uranium and others). Open-pit mining, in particular, requires significant amounts of commercial blasting to dislodge the high volumes of material that have to be moved and processed. An average blasting block at Iscor's Sishen mine, for example, contains about 250 000 tons of material, although a world record was established in April 1981 when 7, 2 million tons of rock was broken during a single blast. The chemical quality of the final products is partly controlled by supplying the primary crusher at the mine with a suitable mixture of so-called run-of-mine ore. To determine which material from a specific blasting block may be sent to the plant, and to which waste dump the remaining material should be assigned, factors such as beneficiation properties of the raw material and the content of various by-products are considered. Samples are typically taken from alternate blast holes for every metre drilled. Each drill sample is divided into two parts by means of a riffler for a washed and unwashed sample. The washed samples are examined and the rock types noted. Subsequently, all the samples are grouped and analysed chemically and the densities of the different rock types are determined. The results are processed and those for the washed and unwashed samples correlated. The blasting blocks in the pit are demarcated by means of whitewash lines, according to the divisions on the blasting-block plans, and they are marked with signs to guide shovel operators. Primary drilling is performed by means of electrically-driven rotary drills. At the Sishen mine, 310 mm diameter blast holes are drilled in all rock types. The following table depicts typical drilling 2 patterns for various rock types: Rock type Pattern (m) Drill depth (m) Hard iron ore 2 x 8, 3 3, 0 Medium-hard iron ore 1 x 9, 3 2, 7 Quartzite 8,2 x 9,4 2, 5 Flagstone 8,2 x 9,4 5 Calcrete 8,1 x 9,3 0 Primary blasting is done at Sishen with Heavy Anfo, an explosive that is manufactured by mine personnel at the emulsion plant on site. The ingredients for the explosive blends are transported by pump trucks to the blasting blocks, where it is mixed and pumped down the blast holes. Good fragmentation of the blasted material is a prerequisite for high loading rates by the loading equipment. At Sishen and other similar mines, a blasting efficiency of 3, 2 tons of rock per kilogram of explosives used, is considered to be acceptable.