Abstract
Aqueous foam provides a dispersion of the gaseous phase in the liquid phase. The commercially available aqueous foam (Denim shaving foam-original) has been investigated for its stability and capability for reducing the extreme thermal and blast effects associated with an energetic material detonation. The dry aqueous foam has evenly distributed bubbles with an average initial size of 15 µm. Different amounts of the C4 explosive were detonated while immersed in the dry aqueous foam having a density 60 kg/m3. The blast wave parameters were measured in the field for scaled distances ranging from 0.39 m/kg1/3 to 1.80 m/kg1/3 based on the cube root law. The dry aqueous foam confinement suppressed the explosion fireball radius up to 80% and quenched the afterburning reactions. An average peak pressure reduction of 70% and positive impulse reduction of ∼62% were observed for hemi-spherical confinement of the dry aqueous foam weighing 1.0 kg–2.75 kg against C4 charges of 82 g–250 g. The shock propagation is attenuated due to the high compressibility of gas bubbles. The dry aqueous foam may be used in emergency circumstances such as against energetic material detonation and lighter improvised explosive device threats to reduce the devastating blast effects. The numerical simulation results using ANSYS AUTODYN for bare charges are in fair agreement with the experimental findings.
Highlights
Escalating acts of terrorism result in loss of invaluable human lives in public places, high profile meeting venues, transportation systems, etc
Peak pressure values obtained with simulation decreased to 4.5 psi at a distance of 2.0 m for 250 g C4 covered in 3.0 kg dry aqueous foam
Microscopic studies reveal that the dry aqueous foam has evenly distributed bubbles with an average initial size of 15 μm that grows to 120 μm in two hours, showing good stability
Summary
Escalating acts of terrorism result in loss of invaluable human lives in public places, high profile meeting venues, transportation systems (land, air, and sea), etc. The detonation of an energetic material is a highly rapid phenomenon and results in production of extremely hot gases with pressures of 3–6 × 106 psi and temperatures exceeding 3000 ○C. When a target is exposed to a blast wave, it experiences a time varying load called impulsive or dynamic loading. This impulsive loading is a function of the mass of the explosive and the stand-off distance and causes severe damage to its vicinity in case of a near field explosion.. The aqueous foam is extremely effective in mitigating both the pressure and the impulse, which results from HE (High Explosive) detonation. The reduction in the pressure is greater than it is for the impulse.
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