Experimental study on mitigation effects of water mist on blast wave

To examine the mitigation characterisitics of blast wave in water mist, a comprehensive series of blast experiments were carried out utilizing a blast-driven shock tube with a 4 m length and 180 mm square inner cross-section. The blast wave was generated by detonating trinitrotoluene charges with masses of 7, 10 and 13 g within the shock tube. Five pressure gauges were installed to measure blast wave pressure within the spray region. In order to create varying water mist properties, a spray system was employed, which covered a distance of 3 m within the experimental setup. Droplet size and distribution were measured using a laser light scattering analyzer. The mitigation effect of water mist with two distinct properties on blast overpressure and impulse was evaluated. Results indicated that the pressure in the spray region raised in two stages. The first stage corresponded to the pressure associated with the transmitted shock wave, while the second stage was attributed to the secondary atomization and relaxation processes of the droplets. The longer the spray region traversed by the blast wave, the greater the mitigation effect on peak overpressure and impulse. Increased shock wave intensity diminished the mitigation effect of water mist on blast loads. Specifically, when water mist with a Sauter mean diameter of 136.04 μm and a volume fraction of 1.72×10−3 was employed, peak pressure values experienced a reduction ranging from 34.2% to 60.9%, while impulse values were reduced by 9% to 54%. On the other hand, when water mist with a Sauter mean diameter of 255.34 μm and a volume fraction of 3.43×10−3 was used, peak pressure values witnessed a reduction ranging from 48.4% to 78.6%, and impulse values were reduced by 14% to 66%. The mitigation coefficient of peak overpressure decreased linearly with increased scaled exchange surface area between blast wave and droplets. © 2023 Explosion and Shock Waves. All rights reserved.