Over forty years of continuous research at UTIAS on nonstationary flows and shock waves

Abstract

Analytical and experimental research on nonsl;ationary shock waves, rarefaction waves and contact surfaces has been conducted continuously at UTIAS since its inception in 1948. Some unique facilities were used to study the properties of planar, cylindrical and spherical shock waves and their interactions. Investigations were also performed on shock-wave structure and boundary layers in ionizing argon, water-vapour condensation in rarefaction waves, magnetogasdynamic flows, and the regions of regular and various types of Mach reflections of oblique shock waves. Explosively-driven implosions have been employed as drivers for projectile launchers and shock tubes, and as a means of producing industrial-type diamonds from graphite, and fusion plasmas in deuterium. The effects of sonic-boom on humans, animals and structures have also formed an important part of the investigations. More recently, interest has focussed on shock waves in dusty gases, the viscous and vibrational structure of weak spherical blast waves in air, and oblique shock-wave reflections. In all of these studies instrumentation and computational methods have played a very important role. A brief survey of this work is given herein and in more detail in the relevant references.

Model for the Performance of Airbreathing Pulse-Detonation Engines

“…This flow configuration is identical to that encountered in shock tubes with positive chambrage. 44 The unsteady expansion in the plenum is very weak after its propagation through the area change, and we neglect it based on the assumption of a large area ratio between the plenum and the valve. 42 The unsteady expansion in the tube accelerates the flow from sonic at the valve plane to supersonic behind the contact surface and decouples the plenum flow from the flow in the detonation tube.…”

“…The flow in the detonation tube is calculated by matching pressure and velocity across the contact surface and solving for the shock Mach number, 44 P…”

Shock-Tube Operation with Laser-Beam-Induced Diaphragm Rupture

“…9 However, in this study the locations of the overpressure measurements in the low-pressure channel are very close to the diaphragm: x/d = 1.4, 4.0, 11.5, 16.5, and 21.5. Moreover, shock-tube operation with such a small pressure difference as that of the present study usually necessitates a long shock formation distance.…”

“…Moreover, shock-tube operation with such a small pressure difference as that of the present study usually necessitates a long shock formation distance. 8,9 Therefore these two experimental factors give a strong impact to the role of diaphragm rupture processes on the shock formation characteristics in the following experiments.…”

Acoustic weapons ‐ a prospective assessment

“…A second problem concerns the possibility of creating such strong shocks. Whereas with focused shock waves (i.e., implosions) pressures of even gigapascals can be achieved in the extremely small focus in the centre of a spherical shock tube, 143 projection to a distance much larger than the source, while avoiding spherical expansion with 1/r 3 shock pressure decrease, seems unachievable (see above). Thus, the possibility of plasma creation at a sizeable distance can be discarded.…”