Blast Mitigation by Water Mist (1) Simulation of Confined Blast Waves

摘要

Effectively minimizing the damage due to onboard explosions and blast waves on naval ships has always been a priority to the Navy. With recent events and the war on terrorism, this need has become important to a much broader base of people to help protect platforms and infrastructure. Water presents a flexible, cost-effective, and clean method for mitigating the effects of the blast wave and has received much attention recently from experimentalists. There is, however, only limited understanding on exactly how to use water most effectively to mitigate blasts. The purpose of this research is to clarify issues related to how water can be used to mitigate blasts within enclosures, and specifically looks at the use of water mist in mitigating blast waves. A parallel, FCT-based simulation technique was developed to examine initial blast properties and long-term pressure development in enclosures for TNT explosions. The simulation technique uses a simplified approach to modeling the area immediately surrounding the explosive (defined as the blast volume), avoiding a costly detonation calculation for the initial explosive. Simulations show that accurate predictions of the initial gas overpressure away from the 'blast' volume can be made with a one-dimensional spherically symmetric model. The one- dimensional solutions do not adequately capture the long-term pressure development within the enclosure. Instabilities in the contact discontinuity that require multi- dimensional simulations become important in driving the secondary Fireball reactions for TNT. Axisymmetric simulations are shown to be adequate in reproducing the long-term overpressure development in enclosures.