Blast mitigation by water mist: the effect of the detonation configuration
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ORIGINAL ARTICLE
Blast mitigation by water mist: the effect of the detonation configuration T. Schunck1 · M. Bastide1 · D. Eckenfels1 · J.‑F. Legendre1 Received: 29 April 2019 / Revised: 27 February 2020 / Accepted: 12 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In this paper, blast mitigation using water mist was evaluated to assess the operational capability of the use of firefighting systems implemented in ships or infrastructures to reduce blast effects. In particular, we tried to determine the mitigation that could be obtained in specific situations. A tunnel equipped with a water mist system enabled us to assess the mitigation impact of water mist on a blast. Blast effects were evaluated using four pressure gauges on the tunnel walls and one pressure gauge at the end of the tunnel. As a first step, we evaluated the mitigation efficiency based on water mist characteristics (the droplet size and the water load) when the charge was detonated inside the mist, the tunnel being either open or closed. Then, we assessed the mitigation efficiency when the charge was detonated outside the mist with only the blast wave propagated in the mist. The reduction in the initial overpressure and the maximum impulse were higher when the charge exploded inside the water mist, and this is most likely due to the quenching of secondary reactions by the water mist. To obtain a better understanding of mitigation mechanisms, shock tube experiments were conducted. The break-up of water drops in the highspeed airstream behind the shock wave was observed, but the presence of mist had no significant effect on the shock wave profile. This is in line with the importance of fireball extinguishment in the mitigation process. Keywords Blast · Mitigation · Water mist
1 Introduction It is a well-known fact that explosion effects can be significantly mitigated if a detonating charge is surrounded by a layer of water. Water can be used in various physical forms. This includes bulk water [1–4], water spray or mist [5–16], and water-based foams [17, 18]. Water mist mitigation concepts can be used to good advantage in the design and operation of new and existing facilities exposed to the threat of an internal explosion, for instance ammunition storage sites or ships. It is also suitable for sensitive facilities, e.g., for Communicated by D. Frost. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00193-020-00960-1) contains supplementary material, which is available to authorized users. * T. Schunck [email protected] 1
ISL, French-German Research Institute of Saint Louis, 5 rue du General Cassagnou, BP 70034, 68301 Saint Louis Cedex, France
the protection against terrorist bombings. In the case of a confined explosion, water mist has the potential to attenuate both the shock pressure and the gas pressure loading developed inside the structure. The water mist system would be activated preventively if there was an imminent risk of detonation. While some
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