Experimental studies on blast mitigation capabilities of conventional dry aqueous foam

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.

Blast and Fragmentation Studies of a Scaled Down Artillery Shell-Simulation and Experimental Approaches

“…Three experiments were conducted with this scaled down model to study the blast and fragmentation effects. PIEZOTRON 211B series pressure transducers were used with Data Acquisition (DAQ) system to measure peak overpressure (Ps) and arrival time (Ta) of the blast wave at different distances [23] from the shell center. The experimental layout is shown in Fig.…”

“…As the computational grid influences the accuracy and reliability of the numerical prediction results [30]. A particle size of 1 is used for packing after optimizing the size for SPH solver [2,23]. Quarter symmetry of the shell is modeled with 28820 nodal points to reduce the computational time.…”

“…The interaction between the two solvers is controlled by an automatic coupling option available in ANSYS AUTODYN. An optimized grid size of 1x1 mm 2 is used for both solvers [2,23]. The air surrounding the shell is filled for ambient pressure of 101kPa (14.7psi) by assigning specific internal energy of 2.068e+5 kJ/kg.…”

Experimental investigations of the response of a portable container to blast, fragmentation, and thermal effects of energetic materials detonation

“…This foam is a two-phase system comprising air cells enclosed by thin liquid films. The measured density of the shaving foam was 60 kg/m 3 (Ahmed and Malik, 2020). Microscopic study of the shaving foam was performed using Olympus microscope.…”

“…The appearance of fireball is the most immediate event upon detonation of an energetic material as evident from Figure 14(b). For bare C4 detonation, the entrapped oxygen within the fireball assists in afterburning reactions and enhances the total energy (Ahmed and Malik, 2020; Lebel et al, 2014). The measured fireball radius from high-speed images was ~0.650 m. The high pressure and temperature results in the formation of a blast wave in air.…”