The combustion process of porous spherical titanium particles with diameters in the range of 100-400㎛ was studied in free fall in air (as single particles), and in composite propellant (as metallic fuel). The particles burning times in air at atmospheric pressure were determined by video recording. Twelve composite propellant containing 60% AP of sieve fraction 180-250㎛, 20% energetic binder, and 20% titanium powder of various size and type (with porous particles and with rolled in ball mill pseudospherical particles) were studied. The propellant burning rate and the agglomeration parameters were determined at pressures of 0.35 MPa in nitrogen and at 0.1 MPa in air. It was established that the smallest agglomerates are formed when titanium powders of the smallest dimensions are used.

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We experimentally and numerically studied the peak-overpressure distribution outside an arbitrarily shaped underground magazine to elucidate its blast pressure-based safe distance. The underground magazine model had two sections: a chamber and a passageway. The safe distance was described as a circle whose radius and center strongly depended on the considered parameters: the internal-diameter ratio between the two sections and the total-internal-lengthto-chamber-diameter ratio. The results of large-scale field explosion experiments using kilogram-order emulsion explosives showed that a smaller internal-diameter ratio and a larger total-internal-length-to-chamber-diameter ratio enhanced the mitigation of the blast wave outside the magazine. The numerically simulated peak overpressures outside the magazine reasonably agreed with the experimental ones. In addition, parametric studies were conducted to describe the blast pressure-based safe distance of an arbitrarily shaped underground magazine.

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