Year

2021

Degree Name

Doctor of Philosophy

Department

School of Civil, Mining and Environmental Engineering

Abstract

The current state of blast resistant design methods is largely reliant on empirical observations of field explosive testing or numerical simulations. While both methods are undoubtedly vital and necessary, they both have inherent limitations. Field trials for performing systematic experimental studies are exceedingly expensive, produce inconsistent results, and are slow in the rate of testing. Conventional blast simulators (shock tubes) enable blast testing to be performed in a safe and controlled laboratory environment but usually do not correctly replicate free-field blast conditions which could lead to deceptive outcomes in regard to target loading and response. The National Facility of Physical Blast Simulation (NFPBS), based on the ‘Advanced Blast Simulator’ (ABS) concept, was established at the University of Wollongong to overcome the shortcomings of conventional blast simulators. This simulator intrinsically replicates the wavedynamics of free-field explosive blast and is unique in its dual-driver mode capability which could operate with compressed gas (CG) or gaseous detonation (GD), providing flexibility in the range of possible blast waveforms. This thesis presents experimental and numerical studies aimed to investigate the propagation of shock waves in an ABS and its performance characteristics.

This thesis first characterises the flow attributes and performance range of the NFPBS ABS for both the CG and GD Driver modes available with the ABS. This is achieved by varying the Driver settings (i.e. compressed gas pressure or explosive gas volume) and standoff distance within the ABS to study the positive and negative phase shock wave parameters. Rankine-Hugoniot equations are employed to relate the experimentally measured peak overpressures with a range of physical properties behind the shock wave. These flow properties are then compared and validated with the ‘Virtual ABS’ (VABS) Computational Fluid Dynamics (CFD) model. Shock wave planarity at different standoff distances is determined using a specially designed calibration wall with pressure transducers mounted across the plane surface and through visualisations from the VABS. Wave diagrams are developed to track the waves travelling within the ABS and reveal differences between the two Driver modes and different ABS configurations. The performance range of the facility is then visualised with pressure-impulse (P-I) maps with comparisons to established equivalent hemispherical TNT threats.

This thesis is unavailable until Thursday, June 02, 2022

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.