Comparison of explosively driven shock tube and open-air blast wave propagation.

Explosive research hinges on the comprehension of shock waves, characterized by rapid pressure spikes and an exponential decay back to ambient conditions. Despite the foundational role of shock waves in understanding high-energy events, consistently replicating them accurately remains a challenge. Real-world scenarios rarely conform to the idealized Friedlander waveform, and obstacles such as terrain and structures often introduce complex shock wave interactions. This study examines the dynamics of shock waves, exploring how their propagation and pressure profiles are shaped by distinct test configurations: unconfined, partially confined, and confined charges. Unconfined configurations have charges situated directly on the ground, and produced shock waves marked by a consistent velocity of 400 ± 1.7 m/s and statistically similar Friedlander waveforms. Partially confined tests, featuring an elevated explosive source, had comparable velocities to unconfined charges, but introduced ground reflections, resulting in positive phase impulses up to 16.5% higher than unconfined tests and were not significantly similar. Peak pressures from the partially confined tests varied with charge height, with some 43.9% lower and others 9.5% higher than the unconfined tests. Confined configurations, created within shock tubes, demonstrated a wide range of variability due to vortex rings and internal reflections, ultimately resulting in positive phase impulse 67.5% higher and peak pressure 2% lower than the unconfined configuration and were not statistically similar when the full waveform was considered. These findings underscore the fundamental role of test configuration in shaping shock wave characteristics and the need to understand the full waveform rather than just the initial peak.