Reproducibility Distinguishability and Correlation of Fireball and Shockwave Dynamics in Explosive Munitions Detonations
Abstract
The classification of battlespace detonations is a particularly challenging problem. The intense infrared radiation produced by the detonation of high explosives is largely unstudied. Furthermore, the time-varying fireball imagery and spectra are driven by many factors. The current study investigates fireball expansion dynamics using high speed, multi-band imagery. Instruments were deployed to three field tests involving improvised explosives in howitzer shells, simulated surface-to-air missiles, and small caliber muzzle flashes. The rate of shockwave expansion for the improvised explosives was determined from apparent index of refraction variations in the visible imagery. Fits of the data to existing drag and explosive models found in the literature, as well as modifications to these models, showed agreement in the near- and mid-fields; the modified models typically predicted the time for the shockwave to arrive a kilometer away to better than 10%; and fit parameters typically had an uncertainty of less than 20%. The shockwave was distinctive within the first 2-10 milliseconds after detonation, then it decayed to an indistinguishable acoustic wave. The area profiles of the fireballs were also examined and found to be highly variable, especially after 10 milliseconds, regardless of munitions type. Scaling relationships between properties of the explosive (mass, specific energies, and theoretical energies) and detonation areas, characteristic times, and properties of the shockwave were assessed for distinguishing weights and types: Efficiency decreased with mass; early-time Mach number and overpressure were primarily dependent on energy release; fireball area increased cubically with specific energies but its time of occurrence decreased cubically. The relationship between fireball and shockwave features was fairly independent of variability, indicating that both fireball and shockwave features scale similarly with variability in detonations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2006
- Accession Number
- ADA450176
Entities
People
- Bryan J. Steward
Organizations
- Air Force Institute of Technology