Previous tests of an explosion driven hydrodynamic shock tube revealed peak pressure data significantly lower than values predicted from the semiempirical scaling laws. It was hypothesized that part of the deviation was due to error in determining shock wave parameters and part might be due to measurement error caused by mechanical vibration of the tube. This investigation was conducted in two parts. In the first part, shock wave parameters were determined using a digital computer and curve fitting techniques to analyze digitized shock wave data. The second part involved determining the frequency components of the shock wave data noise content and comparing this to the dynamic characteristics of the tube which were investigated through an impulse testing technique. From these efforts higher values for the peak pressure were verified but no evidence was found that vibration of the tube caused significant degradation of shock wave test data.

In order to better simulate an explosive underwater environment, a new design of the existing explosion driven hydrodynamic conical shock tube has been proposed. This new concept calls for the removal of part of the old tube to accommodate a distributed breach plug. The distributed breach should enhance shock wave characteristics by minimizing the energy losses associated with plastic deformations which occur at detonation. This report makes use of a finite element program, SAP IV, to investigate the modal characteristics of the new distributed breach design. A dynamic response history analysis has also been performed in order to predict the response of the structure to loads characteristic of an ideal shock wave as it propagates along the tube axis. From these efforts some insight has been gained into the structural feasibility of the new design

An explosive driven, water filled, conical shock tube was designed and evaluated regarding its ability to amplify a charge weight and to produce hydrodynamic spherical shock waves. The results show that the shock waves in the tube are essentially spherical in nature--with an initial exponential shape, peak pressure attenuation as (1/R)1.13 and the time constant spreading roughly as (R).22. The charge weight was amplified by a factor of 3600 compared to a theoretical amplification of 7770. An estimate of the energy absorbed by the breach plug (which houses the charge) during an explosion was performed. The peak pressure data taken from the detonation of number 8 strength blasting caps were seen to satisfy the semiempirical scaling law. However, with the addition of plastic explosive to the blasting cap, peak pressure lower than that predicted by the scaling law was observed. At this time it is felt that a decreasing amplification factor with charge weight is the cause for the lower than predicted peak pressure. More data are needed to verify this hypothesis.

<p>Focusing of strong shock waves in a gas-filled thin test section with various forms of the reflector boundary is investigated. The test section is mounted at the end of the horizontal co-axial shock tube. Two different methods to produce shock waves of various forms are implemented. In the first method the reflector boundary of the test section is exchangeable and four different reflectors are used: a circle, a smooth pentagon, a heptagon and an octagon. It is shown that the form of the converging shock wave is influenced both by the shape of the reflector boundary and by the nonlinear dynamic interaction between the shape of the shock and the propagation velocity of the shock front. Further, the reflected outgoing shock wave is affected by the shape of the reflector through the flow ahead of the shock front. In the second method cylindrical obstacles are placed in the test section at various positions and in various patterns, to create disturbances in the flow that will shape the shock wave. It is shown that it is possible to shape the shock wave in a desired way by means of obstacles. The influence of the supports of the inner body of the co-axial shock tube on the form of the shock is also investigated. A square shaped shock wave is observed close to the center of convergence for the circular and octagonal reflector boundaries but not in any other setups. This square-like shape is believed to be caused by the supports for the inner body. The production of light, as a result of shock convergence, has been preliminary investigated. Flashes of light have been observed during the focusing and reflection process.</p>

Focusing of strong shock waves in a gas-filled thin test section with various forms of the reflector boundary is investigated. The test section is mounted at the end of the horizontal co-axial shock tube. Two different methods to produce shock waves of various forms are implemented. In the first method the reflector boundary of the test section is exchangeable and four different reflectors are used: a circle, a smooth pentagon, a heptagon and an octagon. It is shown that the form of the converging shock wave is influenced both by the shape of the reflector boundary and by the nonlinear dynamic interaction between the shape of the shock and the propagation velocity of the shock front. Further, the reflected outgoing shock wave is affected by the shape of the reflector through the flow ahead of the shock front. In the second method cylindrical obstacles are placed in the test section at various positions and in various patterns, to create disturbances in the flow that will shape the shock wave. It is shown that it is possible to shape the shock wave in a desired way by means of obstacles. The influence of the supports of the inner body of the co-axial shock tube on the form of the shock is also investigated. A square shaped shock wave is observed close to the center of convergence for the circular and octagonal reflector boundaries but not in any other setups. This square-like shape is believed to be caused by the supports for the inner body. The production of light, as a result of shock convergence, has been preliminary investigated. Flashes of light have been observed during the focusing and reflection process. / QC 20101126

No description available.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 73-87).

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Thadhani, Naresh; Committee Member: Das, Suman; Committee Member: Fajardo, Mario; Committee Member: Zhou, Min.

Thesis (M. Eng. Sc.)--University of Queensland, 2001. / Includes bibliographical references.

High-speed particle dispersion research is motivated by the energy release enhancement of explosives containing solid particles. In the initial explosive dispersal, a dense gas-solid flow can exist where the physics of phase interactions are not well understood. A dense particle flow is generated by the interaction of a shock wave with an initially stationary packed granular bed. The initial packed granular bed is produced by compressing loose aluminum oxide powder into a 6.35 mm thick wafer with a particle volume fraction of 0.48. The wafer is positioned inside the shock tube, uniformly filling the entire cross-section. This results in a clean experiment where no flow obstructing support structures are present. Through high-speed shadowgraph imaging and pressure measurements along the length of the channel, detailed information about the particle-shock interaction was obtained. Due to the limited strength of the Mach 2 incident shock wave, no transmitted shock wave is produced. The initial “solid-like” response of the particle wafer acceleration forms a series of compression waves that coalesce to form a shock wave. Breakup is initiated along the periphery of the wafer as the result of shear that forms due to the fixed boundary condition. Particle break-up starts at local failure sites that result in the formation of particle jets that extend ahead of the accelerating, largely intact, wafer core. In a circular tube the failure sites are uniformly distributed along the wafer circumference. In a square channel, the failure sites, and the subsequent particle jets, initially form at the corners due to the enhanced shear. The wafer breakup subsequently spreads to the edges forming a highly non-uniform particle cloud. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-09-25 14:15:37.615